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Question 1
Incorrect
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You are assisting in an open right adrenalectomy for a large adrenal adenoma in a slightly older patient. The consultant is momentarily distracted and you take the initiative to pull the adrenal into the wound to improve visibility. Unfortunately, this maneuver results in brisk bleeding. The most likely culprit vessel responsible for this bleeding is:
- Portal vein
- Phrenic vein
- Right renal vein
- Superior mesenteric vein
- Inferior vena cava
The vessel in question drains directly via a very short vessel and if not carefully sutured, it may become avulsed off the IVC. The best management approach for this injury involves the use of a Satinsky clamp and a 6/0 prolene suture.Your Answer: Phrenic vein
Correct Answer: Inferior vena cava
Explanation:The vessel drains directly and is connected by a short pathway. If the sutures are not tied with caution, it could potentially detach from the IVC. In such a scenario, the recommended approach would be to use a Satinsky clamp and a 6/0 prolene suture to manage the injury.
Adrenal Gland Anatomy
The adrenal glands are located superomedially to the upper pole of each kidney. The right adrenal gland is posteriorly related to the diaphragm, inferiorly related to the kidney, medially related to the vena cava, and anteriorly related to the hepato-renal pouch and bare area of the liver. On the other hand, the left adrenal gland is postero-medially related to the crus of the diaphragm, inferiorly related to the pancreas and splenic vessels, and anteriorly related to the lesser sac and stomach.
The arterial supply of the adrenal glands is through the superior adrenal arteries from the inferior phrenic artery, middle adrenal arteries from the aorta, and inferior adrenal arteries from the renal arteries. The right adrenal gland drains via one central vein directly into the inferior vena cava, while the left adrenal gland drains via one central vein into the left renal vein.
In summary, the adrenal glands are small but important endocrine glands located above the kidneys. They have a unique blood supply and drainage system, and their location and relationships with other organs in the body are crucial for their proper functioning.
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This question is part of the following fields:
- Renal System
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Question 2
Correct
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A 43-year-old man presents to his GP with a 3-month history of occasional frank haematuria. He has come in today as he began to experience intense, cramping loin pain over the weekend. Upon further questioning, the patient discloses that he has unintentionally lost 7kg of weight over the last 3 months.
The patient has been a smoker of 20 cigarettes a day for the past 26 years and has a BMI of 36kg/m2.
During the examination, a mass is palpated when balloting the kidneys. There are no other signs to elicit on examination.
What is the most common histological subtype given the likely diagnosis?Your Answer: Clear cell
Explanation:The most common subtype of renal cell carcinoma is clear cell, while squamous epithelial is a subtype of bladder cancer and not typically associated with renal carcinoma.
Renal cell cancer, also known as hypernephroma, is a primary renal neoplasm that accounts for 85% of cases. It originates from the proximal renal tubular epithelium and is commonly associated with smoking and conditions such as von Hippel-Lindau syndrome and tuberous sclerosis. The clear cell subtype is the most prevalent, comprising 75-85% of tumors.
Renal cell cancer is more common in middle-aged men and may present with classical symptoms such as haematuria, loin pain, and an abdominal mass. Other features include endocrine effects, such as the secretion of erythropoietin, parathyroid hormone-related protein, renin, and ACTH. Metastases are present in 25% of cases at presentation, and paraneoplastic syndromes such as Stauffer syndrome may also occur.
The T category criteria for renal cell cancer are based on tumor size and extent of invasion. Management options include partial or total nephrectomy, depending on the tumor size and extent of disease. Patients with a T1 tumor are typically offered a partial nephrectomy, while alpha-interferon and interleukin-2 may be used to reduce tumor size and treat metastases. Receptor tyrosine kinase inhibitors such as sorafenib and sunitinib have shown superior efficacy compared to interferon-alpha.
In summary, renal cell cancer is a common primary renal neoplasm that is associated with various risk factors and may present with classical symptoms and endocrine effects. Management options depend on the extent of disease and may include surgery and targeted therapies.
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This question is part of the following fields:
- Renal System
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Question 3
Correct
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A 65-year-old man comes to the clinic for a medication review. He reports no negative effects and wishes to continue his current treatment. After conducting a blood test, you notice that his serum potassium level is slightly elevated. Which of the following frequently prescribed drugs is linked to an increase in serum potassium?
Your Answer: Ramipril
Explanation:Ramipril is the correct answer. Before starting ACE inhibitor therapy, a baseline potassium level is measured because these drugs can cause an increase in serum potassium.
Loop diuretics like furosemide can cause hypokalaemia and hyponatraemia.
Salbutamol does not lead to hyperkalaemia and can actually be used to lower serum potassium levels in emergency situations.
Taking paracetamol within recommended doses does not affect potassium levels.
Drugs and their Effects on Potassium Levels
Many commonly prescribed drugs have the potential to alter the levels of potassium in the bloodstream. Some drugs can decrease the amount of potassium in the blood, while others can increase it.
Drugs that can decrease serum potassium levels include thiazide and loop diuretics, as well as acetazolamide. On the other hand, drugs that can increase serum potassium levels include ACE inhibitors, angiotensin-2 receptor blockers, spironolactone, and potassium-sparing diuretics like amiloride and triamterene. Additionally, taking potassium supplements like Sando-K or Slow-K can also increase potassium levels in the blood.
It’s important to note that the above list does not include drugs used to temporarily decrease serum potassium levels for patients with hyperkalaemia, such as salbutamol or calcium resonium.
Overall, it’s crucial for healthcare providers to be aware of the potential effects of medications on potassium levels and to monitor patients accordingly.
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This question is part of the following fields:
- Renal System
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Question 4
Incorrect
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A 35-year-old female patient complains of chronic flank pain. Her family history reveals a brother with similar symptoms and a mother who died from a subarachnoid haemorrhage. Bilateral renal ultrasound shows multiple cysts. Which chromosome is most likely to be affected in this genetic disorder?
Your Answer: 3
Correct Answer: 16
Explanation:Autosomal dominant polycystic kidney disease (ADPKD) is a commonly inherited kidney disease that affects 1 in 1,000 Caucasians. The disease is caused by mutations in two genes, PKD1 and PKD2, which produce polycystin-1 and polycystin-2 respectively. ADPKD type 1 accounts for 85% of cases, while ADPKD type 2 accounts for 15% of cases. ADPKD type 1 is caused by a mutation in the PKD1 gene on chromosome 16, while ADPKD type 2 is caused by a mutation in the PKD2 gene on chromosome 4. ADPKD type 1 tends to present with renal failure earlier than ADPKD type 2.
To screen for ADPKD in relatives of affected individuals, an abdominal ultrasound is recommended. The diagnostic criteria for ultrasound include the presence of two cysts, either unilateral or bilateral, if the individual is under 30 years old. If the individual is between 30-59 years old, two cysts in both kidneys are required for diagnosis. If the individual is over 60 years old, four cysts in both kidneys are necessary for diagnosis.
For some patients with ADPKD, tolvaptan, a vasopressin receptor 2 antagonist, may be an option to slow the progression of cyst development and renal insufficiency. However, NICE recommends tolvaptan only for adults with ADPKD who have chronic kidney disease stage 2 or 3 at the start of treatment, evidence of rapidly progressing disease, and if the company provides it with the agreed discount in the patient access scheme.
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This question is part of the following fields:
- Renal System
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Question 5
Incorrect
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A 26-year-old man is involved in a car crash and develops oliguria with worsening renal function. How can acute tubular necrosis be differentiated from pre-renal azotemia in this case?
Your Answer: Increased urine specific gravity
Correct Answer: No response to intravenous fluids
Explanation:Inability to respond to intravenous fluids is observed in acute tubular necrosis due to the damage originating from the renal system itself, rather than being caused by a reduction in volume.
Understanding the Difference between Acute Tubular Necrosis and Prerenal Uraemia
Acute kidney injury can be caused by various factors, including prerenal uraemia and acute tubular necrosis. It is important to differentiate between the two to determine the appropriate treatment. Prerenal uraemia occurs when the kidneys hold on to sodium to preserve volume, leading to decreased blood flow to the kidneys. On the other hand, acute tubular necrosis is caused by damage to the kidney tubules, which can be due to various factors such as toxins, infections, or ischemia.
To differentiate between the two, several factors can be considered. In prerenal uraemia, the urine sodium level is typically less than 20 mmol/L, while in acute tubular necrosis, it is usually greater than 40 mmol/L. The urine osmolality is also higher in prerenal uraemia, typically above 500 mOsm/kg, while in acute tubular necrosis, it is usually below 350 mOsm/kg. The fractional sodium excretion is less than 1% in prerenal uraemia, while it is greater than 1% in acute tubular necrosis. Additionally, the response to fluid challenge is typically good in prerenal uraemia, while it is poor in acute tubular necrosis.
Other factors that can help differentiate between the two include the serum urea:creatinine ratio, fractional urea excretion, urine:plasma osmolality, urine:plasma urea, specific gravity, and urine sediment. By considering these factors, healthcare professionals can accurately diagnose and treat acute kidney injury.
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This question is part of the following fields:
- Renal System
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Question 6
Incorrect
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During a 5-year-old male child's routine check-up, a doctor observes macroglossia, hepatomegaly and renomegaly along with a characteristic ear crease. The child was born at 38 weeks gestation and had a prolonged spontaneous vaginal delivery. His birth weight was 4 kg (8Ib 13oz). He had neonatal hypoglycaemia during the first 12 hours which was treated with IV dextrose. The doctor suspects Beckwith-Wiedemann syndrome. What childhood cancers are associated with this syndrome?
Your Answer: Acute lymphoblastic leukaemia (ALL)
Correct Answer: Wilms tumour (nephroblastoma)
Explanation:Beckwith-Wiedemann syndrome (BWS) is a rare condition that causes excessive growth in children and increases their risk of developing tumors. It affects approximately 1 in 10,300 to 13,700 people. Symptoms of BWS include large body size, enlarged tongue, protruding belly button or hernia, ear creases or pits, enlarged organs in the abdomen, and low blood sugar in newborns. The most common cancer associated with BWS is Wilms tumor, although other childhood cancers can also occur.
Wilms’ Tumour: A Common Childhood Malignancy
Wilms’ tumour, also known as nephroblastoma, is a prevalent type of cancer in children, with a median age of diagnosis at 3 years old. It is often associated with Beckwith-Wiedemann syndrome, hemihypertrophy, and a loss-of-function mutation in the WT1 gene on chromosome 11. The most common presenting feature is an abdominal mass, which is usually painless, but other symptoms such as haematuria, flank pain, anorexia, and fever may also occur. In 95% of cases, the tumour is unilateral, and metastases are found in 20% of patients, most commonly in the lungs.
If a child presents with an unexplained enlarged abdominal mass, it is crucial to arrange a paediatric review within 48 hours to rule out Wilms’ tumour. The management of this cancer typically involves nephrectomy, chemotherapy, and radiotherapy if the disease is advanced. Fortunately, the prognosis for Wilms’ tumour is good, with an 80% cure rate.
Histologically, Wilms’ tumour is characterized by epithelial tubules, areas of necrosis, immature glomerular structures, stroma with spindle cells, and small cell blastomatous tissues resembling the metanephric blastema. Overall, early detection and prompt treatment are essential for a successful outcome in children with Wilms’ tumour.
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This question is part of the following fields:
- Renal System
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Question 7
Correct
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What electrolyte imbalance is probable in a patient experiencing diarrhea and a palpable soft mass during digital rectal examination?
Your Answer: Hypokalaemia
Explanation:Rectal secretions from large villous adenomas of the rectum can cause hypokalaemia due to their high potassium content, which is a result of the marked secretory activity of the adenomas.
Understanding Hypokalaemia and its Causes
Hypokalaemia is a condition characterized by low levels of potassium in the blood. Potassium and hydrogen ions are competitors, and as potassium levels decrease, more hydrogen ions enter the cells. Hypokalaemia can occur with either alkalosis or acidosis. In cases of alkalosis, hypokalaemia may be caused by vomiting, thiazide and loop diuretics, Cushing’s syndrome, or Conn’s syndrome. On the other hand, hypokalaemia with acidosis may be caused by diarrhoea, renal tubular acidosis, acetazolamide, or partially treated diabetic ketoacidosis.
It is important to note that magnesium deficiency may also cause hypokalaemia. In such cases, normalizing potassium levels may be difficult until the magnesium deficiency has been corrected. Understanding the causes of hypokalaemia can help in its diagnosis and treatment.
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This question is part of the following fields:
- Renal System
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Question 8
Correct
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A 54-year-old man visits the clinic after his spouse was diagnosed with hypertension and advised him to get his blood pressure checked. He has no symptoms. Upon measurement, his blood pressure is 155/92 mmHg. To further evaluate, a 24-hour blood pressure monitoring is scheduled. During the consultation, you discuss the physiology of blood pressure and mention the significance of the renin-angiotensin-aldosterone system in maintaining blood pressure homeostasis. Can you identify the primary site of aldosterone action in the kidney?
Your Answer: Distal convoluted tubule and collecting duct of the nephron
Explanation:Aldosterone functions in the distal convoluted tubule and collecting ducts of the nephron. Spironolactone is a diuretic that preserves potassium levels by blocking aldosterone receptors. The loop of Henle and Bowman’s capsule are located closer to the beginning of the nephron. Prostaglandins regulate the afferent arteriole of the glomerulus, causing vasodilation. NSAIDs can lead to renal failure by inhibiting prostaglandin production. The vasa recta are straight capillaries that run parallel to the loop of Henle in the kidney. To confirm a diagnosis of hypertension, NICE recommends a 24-hour ambulatory blood pressure reading to account for the potential increase in blood pressure in clinical settings.
Aldosterone is a hormone that is primarily produced by the adrenal cortex in the zona glomerulosa. Its main function is to stimulate the reabsorption of sodium from the distal tubules, which results in the excretion of potassium. It is regulated by various factors such as angiotensin II, potassium, and ACTH, which increase its secretion. However, when there is an overproduction of aldosterone, it can lead to primary hyperaldosteronism, which is a common cause of secondary hypertension. This condition can be caused by an adrenal adenoma, which is also known as Conn’s syndrome. It is important to note that spironolactone, an aldosterone antagonist, can cause hyperkalemia.
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This question is part of the following fields:
- Renal System
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Question 9
Incorrect
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A 54-year-old man was admitted 2 weeks ago for pneumonia and was prescribed oral antibiotics. However, the antibiotics were changed after he developed a Clostridium difficile infection 9 days ago, which he is still recovering from. Fortunately, his pneumonia has improved.
He has no significant medical history and is not taking any long-term medications.
What are the expected results of his arterial blood gas test?Your Answer: Raised anion gap metabolic alkalosis
Correct Answer: Normal anion gap metabolic acidosis
Explanation:Diarrhoea caused by a Clostridium difficile infection can result in a normal anion gap metabolic acidosis due to the loss of bicarbonate. The body compensates for this by increasing chloride concentration, which maintains a normal anion gap. Low anion gap metabolic acidosis, normal anion gap metabolic alkalosis, and raised anion gap metabolic acidosis are all incorrect as they do not accurately reflect the compensatory mechanisms in this scenario.
Understanding Metabolic Acidosis
Metabolic acidosis is a condition that can be classified based on the anion gap, which is calculated by subtracting the sum of chloride and bicarbonate from the sum of sodium and potassium. The normal range for anion gap is 10-18 mmol/L. If a question provides the chloride level, it may be an indication to calculate the anion gap.
Hyperchloraemic metabolic acidosis is a type of metabolic acidosis with a normal anion gap. It can be caused by gastrointestinal bicarbonate loss, prolonged diarrhea, ureterosigmoidostomy, fistula, renal tubular acidosis, drugs like acetazolamide, ammonium chloride injection, and Addison’s disease. On the other hand, raised anion gap metabolic acidosis is caused by lactate, ketones, urate, acid poisoning, and other factors.
Lactic acidosis is a type of metabolic acidosis that is caused by high lactate levels. It can be further classified into two types: lactic acidosis type A, which is caused by sepsis, shock, hypoxia, and burns, and lactic acidosis type B, which is caused by metformin. Understanding the different types and causes of metabolic acidosis is important in diagnosing and treating the condition.
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This question is part of the following fields:
- Renal System
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Question 10
Correct
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A 37-year-old woman presents to rheumatology with complaints of fatigue and arthralgia persisting for the past 3 months. During her evaluation, a urine dipstick test reveals proteinuria, and renal biopsies reveal histological evidence of proliferative 'wire-loop' glomerulonephritis.
What is the probable diagnosis?Your Answer: Systemic lupus erythematosus (SLE)
Explanation:Renal Complications in Systemic Lupus Erythematosus
Systemic lupus erythematosus (SLE) can lead to severe renal complications, including lupus nephritis, which can result in end-stage renal disease. Regular check-ups with urinalysis are necessary to detect proteinuria in SLE patients. The WHO classification system categorizes lupus nephritis into six classes, with class IV being the most common and severe form. Renal biopsy shows characteristic findings such as endothelial and mesangial proliferation, a wire-loop appearance, and subendothelial immune complex deposits.
Management of lupus nephritis involves treating hypertension and using glucocorticoids with either mycophenolate or cyclophosphamide for initial therapy in cases of focal (class III) or diffuse (class IV) lupus nephritis. Mycophenolate is generally preferred over azathioprine for subsequent therapy to decrease the risk of developing end-stage renal disease. Early detection and proper management of renal complications in SLE patients are crucial to prevent irreversible damage to the kidneys.
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This question is part of the following fields:
- Renal System
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Question 11
Incorrect
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An 71-year-old man arrives at the emergency department complaining of severe back pain that started 2 hours ago. The pain is radiating from his flank to his groin and comes and goes in waves. He had a kidney stone 2 months ago. A CT scan reveals a hyperdense calculus in his left ureter. His serum calcium level is 2.1 mmol/L (normal range: 2.2-2.6) and his urine calcium level is 9.2 mmol/24hours (normal range: 2.5-7.5). What medication is the most appropriate to reduce the risk of further renal stones?
Your Answer: Bumetanide
Correct Answer: Bendroflumethiazide
Explanation:Thiazide diuretics, specifically bendroflumethiazide, can be used to decrease calcium excretion and stone formation in patients with hypercalciuria and renal stones. The patient’s urinary calcium levels indicate hypercalciuria, which can be managed with thiazide diuretics. Bumetanide and furosemide, both loop diuretics, are not effective in managing hypercalciuria and renal stones. Denosumab, an antibody used for hypercalcaemia associated with malignancy, is not used in the management of renal stones.
Management and Prevention of Renal Stones
Renal stones, also known as kidney stones, can cause severe pain and discomfort. The British Association of Urological Surgeons (BAUS) has published guidelines on the management of acute ureteric/renal colic. Initial management includes the use of NSAIDs as the analgesia of choice for renal colic, with caution taken when prescribing certain NSAIDs due to increased risk of cardiovascular events. Alpha-adrenergic blockers are no longer routinely recommended, but may be beneficial for patients amenable to conservative management. Initial investigations include urine dipstick and culture, serum creatinine and electrolytes, FBC/CRP, and calcium/urate levels. Non-contrast CT KUB is now recommended as the first-line imaging for all patients, with ultrasound having a limited role.
Most renal stones measuring less than 5 mm in maximum diameter will pass spontaneously within 4 weeks. However, more intensive and urgent treatment is indicated in the presence of ureteric obstruction, renal developmental abnormality, and previous renal transplant. Treatment options include lithotripsy, nephrolithotomy, ureteroscopy, and open surgery. Shockwave lithotripsy involves generating a shock wave externally to the patient, while ureteroscopy involves passing a ureteroscope retrograde through the ureter and into the renal pelvis. Percutaneous nephrolithotomy involves gaining access to the renal collecting system and performing intra corporeal lithotripsy or stone fragmentation. The preferred treatment option depends on the size and complexity of the stone.
Prevention of renal stones involves lifestyle modifications such as high fluid intake, low animal protein and salt diet, and thiazide diuretics to increase distal tubular calcium resorption. Calcium stones may also be due to hypercalciuria, which can be managed with thiazide diuretics. Oxalate stones can be managed with cholestyramine and pyridoxine, while uric acid stones can be managed with allopurinol and urinary alkalinization with oral bicarbonate.
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This question is part of the following fields:
- Renal System
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Question 12
Incorrect
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A 47-year-old man is under the care of an ophthalmologist for open angle glaucoma. He visits his GP to express his worries about the medication prescribed after reading online information. What is the medication that the ophthalmologist has prescribed, which can function as a diuretic by acting on the proximal convoluted tubule of the kidney?
Your Answer: Bendroflumethiazide (thiazide diuretic)
Correct Answer: Acetazolamide (carbonic anhydrase inhibitor)
Explanation:Diuretic drugs are classified into three major categories based on the location where they inhibit sodium reabsorption. Loop diuretics act on the thick ascending loop of Henle, thiazide diuretics on the distal tubule and connecting segment, and potassium sparing diuretics on the aldosterone-sensitive principal cells in the cortical collecting tubule. Sodium is reabsorbed in the kidney through Na+/K+ ATPase pumps located on the basolateral membrane, which return reabsorbed sodium to the circulation and maintain low intracellular sodium levels. This ensures a constant concentration gradient.
The physiological effects of commonly used diuretics vary based on their site of action. furosemide, a loop diuretic, inhibits the Na+/K+/2Cl- carrier in the ascending limb of the loop of Henle and can result in up to 25% of filtered sodium being excreted. Thiazide diuretics, which act on the distal tubule and connecting segment, inhibit the Na+Cl- carrier and typically result in between 3 and 5% of filtered sodium being excreted. Finally, spironolactone, a potassium sparing diuretic, inhibits the Na+/K+ ATPase pump in the cortical collecting tubule and typically results in between 1 and 2% of filtered sodium being excreted.
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This question is part of the following fields:
- Renal System
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Question 13
Correct
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You are working in a GP clinic. A 32-year-old woman has multiple sclerosis. After taking a history and examining her, you diagnose her with chronic urinary retention.
What nerves are most likely affected by demyelination in this case?Your Answer: Pelvic splanchnic
Explanation:The pelvic splanchnic nerves provide parasympathetic innervation to the bladder. In cases of chronic urinary retention, damage to these nerves may be the cause. The greater splanchnic nerves supply the foregut of the gastrointestinal tract, while the lesser splanchnic nerves supply the midgut. Sympathetic innervation of the bladder comes from the hypogastric nerve plexuses, and the lumbar splanchnic nerves innervate the smooth muscles and glands of the pelvis.
Bladder Anatomy and Innervation
The bladder is a three-sided pyramid-shaped organ located in the pelvic cavity. Its apex points towards the symphysis pubis, while the base lies anterior to the rectum or vagina. The bladder’s inferior aspect is retroperitoneal, while the superior aspect is covered by peritoneum. The trigone, the least mobile part of the bladder, contains the ureteric orifices and internal urethral orifice. The bladder’s blood supply comes from the superior and inferior vesical arteries, while venous drainage occurs through the vesicoprostatic or vesicouterine venous plexus. Lymphatic drainage occurs mainly to the external iliac and internal iliac nodes, with the obturator nodes also playing a role. The bladder is innervated by parasympathetic nerve fibers from the pelvic splanchnic nerves and sympathetic nerve fibers from L1 and L2 via the hypogastric nerve plexuses. The parasympathetic fibers cause detrusor muscle contraction, while the sympathetic fibers innervate the trigone muscle. The external urethral sphincter is under conscious control, and voiding occurs when the rate of neuronal firing to the detrusor muscle increases.
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This question is part of the following fields:
- Renal System
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Question 14
Incorrect
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A 56-year-old man presents to the outpatient cardiology clinic complaining of fatigue and weight gain. He has been diagnosed with type II diabetes for 14 years and has been taking metformin to control his blood sugar levels. An echocardiogram reveals a globally dilated left ventricle with a reduced ejection fraction of approximately 30%, and his NT-proBNP level is 1256 (<125 pg/mL). The healthcare provider decides to initiate empagliflozin therapy due to its cardioprotective effects in patients with heart failure with reduced ejection fraction. What is the primary mechanism of action for this new medication?
Your Answer: Ascending loop of Henle
Correct Answer: Proximal convoluted tubule
Explanation:Glucose reabsorption within the nephron is mainly concentrated in the proximal convoluted tubule.
The Loop of Henle and its Role in Renal Physiology
The Loop of Henle is a crucial component of the renal system, located in the juxtamedullary nephrons and running deep into the medulla. Approximately 60 litres of water containing 9000 mmol sodium enters the descending limb of the loop of Henle in 24 hours. The osmolarity of fluid changes and is greatest at the tip of the papilla. The thin ascending limb is impermeable to water, but highly permeable to sodium and chloride ions. This loss means that at the beginning of the thick ascending limb the fluid is hypo osmotic compared with adjacent interstitial fluid. In the thick ascending limb, the reabsorption of sodium and chloride ions occurs by both facilitated and passive diffusion pathways. The loops of Henle are co-located with vasa recta, which have similar solute compositions to the surrounding extracellular fluid, preventing the diffusion and subsequent removal of this hypertonic fluid. The energy-dependent reabsorption of sodium and chloride in the thick ascending limb helps to maintain this osmotic gradient. Overall, the Loop of Henle plays a crucial role in regulating the concentration of solutes in the renal system.
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This question is part of the following fields:
- Renal System
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Question 15
Incorrect
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A 38-year-old man arrives at the emergency department with sudden-onset acute left flank pain that started an hour ago. He describes the pain as colicky and radiating down to his groin. The man is also experiencing nausea and vomiting and appears restless. He has no significant medical or surgical history and has never been hospitalized before. His body mass index is 31 kg per m2. Upon examination, his heart rate is 94 beats per minute, respiratory rate is 19 breaths per minute, and blood pressure is 136/79 mmHg. Radiographic studies confirm the presence of stones in the left ureter. What is a characteristic of the most common type of kidney stones?
Your Answer: Hexagonal-shaped crystals
Correct Answer: Envelope-shaped crystals
Explanation:The patient displayed symptoms consistent with urolithiasis, specifically ureterolithiasis, as imaging revealed the presence of stones in the left ureter. Kidney stones are commonly composed of calcium oxalate, but can also consist of calcium phosphate, ammonium magnesium phosphate, uric acid, or cystine, depending on urine pH and other factors.
Uric acid stones are characterized by diamond or rhomboid-shaped crystals and are often found in individuals with hyperuricemia. Calcium oxalate stones, which have envelope-shaped crystals, are the most common type and are associated with low water intake and dehydration. Cystine stones, with hexagonal-shaped crystals, are prevalent in patients with the genetic condition COLA, which impairs the reabsorption of certain amino acids in the proximal convoluted tubule. Ammonium magnesium phosphate stones, also known as struvites, have coffin-lid shaped crystals and are common in individuals with urinary tract infections caused by urease-producing organisms, such as Klebsiella, Staphylococcus saprophyticus, and Proteus mirabilis. Preventive strategies should be a focus of future management for patients diagnosed with kidney stones.
Renal stones can be classified into different types based on their composition. Calcium oxalate stones are the most common, accounting for 85% of all calculi. These stones are formed due to hypercalciuria, hyperoxaluria, and hypocitraturia. They are radio-opaque and may also bind with uric acid stones. Cystine stones are rare and occur due to an inherited recessive disorder of transmembrane cystine transport. Uric acid stones are formed due to purine metabolism and may precipitate when urinary pH is low. Calcium phosphate stones are associated with renal tubular acidosis and high urinary pH. Struvite stones are formed from magnesium, ammonium, and phosphate and are associated with chronic infections. The pH of urine can help determine the type of stone present, with calcium phosphate stones forming in normal to alkaline urine, uric acid stones forming in acidic urine, and struvate stones forming in alkaline urine. Cystine stones form in normal urine pH.
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This question is part of the following fields:
- Renal System
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Question 16
Incorrect
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A 46-year-old patient visits his doctor 5 days after his last appointment, worried about passing very small amounts of urine for the past 4 days. He was prescribed gentamicin for an infection during his last visit. The doctor suspects gentamicin-induced nephrotoxicity and conducts an examination, finding no abnormalities and normal blood pressure and temperature. The patient's fractional excretion of urine is greater than 4%, and a urine sample is sent to the lab for microscopy, culture, and sensitivity. What would be observed on microscopy if the doctor's suspicion is correct?
Your Answer: Red cell casts
Correct Answer: Brown granular casts
Explanation:The clinical significance of various laboratory findings is summarized in the table below:
Laboratory Finding Clinical Significance
Elevated creatinine and BUN Indicates impaired kidney function
Low serum albumin Indicates malnutrition or liver disease
Elevated liver enzymes Indicates liver damage or disease
Elevated glucose Indicates diabetes or impaired glucose tolerance
Elevated potassium Indicates kidney dysfunction or medication side effect
Elevated sodium Indicates dehydration or excessive sodium intake
Elevated nitrites Indicates urinary tract infection
Elevated white blood cells Indicates infection or inflammation
Elevated red blood cells Indicates dehydration or kidney disease
Elevated platelets Indicates clotting disorder or inflammationDifferent Types of Urinary Casts and Their Significance
Urine contains various types of urinary casts that can provide important information about the underlying condition of the patient. Hyaline casts, for instance, are composed of Tamm-Horsfall protein that is secreted by the distal convoluted tubule. These casts are commonly seen in normal urine, after exercise, during fever, or with loop diuretics. On the other hand, brown granular casts in urine are indicative of acute tubular necrosis.
In prerenal uraemia, the urinary sediment appears ‘bland’, which means that there are no significant abnormalities in the urine. Lastly, red cell casts are associated with nephritic syndrome, which is a condition characterized by inflammation of the glomeruli in the kidneys. By analyzing the type of urinary casts present in the urine, healthcare professionals can diagnose and manage various kidney diseases and disorders. Proper identification and interpretation of urinary casts can help in the early detection and treatment of kidney problems.
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This question is part of the following fields:
- Renal System
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Question 17
Incorrect
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What are the probable outcomes of the discharge of vasopressin from the pituitary gland?
Your Answer: Increased permeability of the mesangial cells to glucose
Correct Answer: Increased water permeability of the distal tubule cells of the kidney
Explanation:Aquaporin channels are inserted into the apical membrane of the distal tubule and collecting ducts as a result of ADH (vasopressin).
The Loop of Henle and its Role in Renal Physiology
The Loop of Henle is a crucial component of the renal system, located in the juxtamedullary nephrons and running deep into the medulla. Approximately 60 litres of water containing 9000 mmol sodium enters the descending limb of the loop of Henle in 24 hours. The osmolarity of fluid changes and is greatest at the tip of the papilla. The thin ascending limb is impermeable to water, but highly permeable to sodium and chloride ions. This loss means that at the beginning of the thick ascending limb the fluid is hypo osmotic compared with adjacent interstitial fluid. In the thick ascending limb, the reabsorption of sodium and chloride ions occurs by both facilitated and passive diffusion pathways. The loops of Henle are co-located with vasa recta, which have similar solute compositions to the surrounding extracellular fluid, preventing the diffusion and subsequent removal of this hypertonic fluid. The energy-dependent reabsorption of sodium and chloride in the thick ascending limb helps to maintain this osmotic gradient. Overall, the Loop of Henle plays a crucial role in regulating the concentration of solutes in the renal system.
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This question is part of the following fields:
- Renal System
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Question 18
Incorrect
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Which of the following is the primary location for the release of dehydroepiandrosterone in individuals?
Your Answer: Zona fasciculata of the adrenal gland
Correct Answer: Zona reticularis of the adrenal gland
Explanation:The adrenal cortex can be remembered with the mnemonic GFR-ACD, where DHEA is a hormone with androgenic effects that is primarily secreted by the adrenal gland.
The renin-angiotensin-aldosterone system is a complex system that regulates blood pressure and fluid balance in the body. The adrenal cortex is divided into three zones, each producing different hormones. The zona glomerulosa produces mineralocorticoids, mainly aldosterone, which helps regulate sodium and potassium levels in the body. Renin is an enzyme released by the renal juxtaglomerular cells in response to reduced renal perfusion, hyponatremia, and sympathetic nerve stimulation. It hydrolyses angiotensinogen to form angiotensin I, which is then converted to angiotensin II by angiotensin-converting enzyme in the lungs. Angiotensin II has various actions, including causing vasoconstriction, stimulating thirst, and increasing proximal tubule Na+/H+ activity. It also stimulates aldosterone and ADH release, which causes retention of Na+ in exchange for K+/H+ in the distal tubule.
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This question is part of the following fields:
- Renal System
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Question 19
Incorrect
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A patient diagnosed with chronic primary hyperparathyroidism underwent parathyroidectomy and is now being seen for follow-up. The patient's postoperative blood results are as follows:
Parathyroid hormone: 1.8 pmol/L (normal range: 1.6 - 6.9 pmol/L)
Corrected calcium: 1.7 mmol/L (normal range: 2.1 - 2.6 mmol/L)
Phosphate: 0.1 mmol/L (normal range: 0.1 - 0.8 mmol/L)
What is the most likely explanation for these results?Your Answer:
Correct Answer: Hungry bone syndrome
Explanation:The sudden drop in previously high parathyroid hormone levels can lead to hungry bone syndrome, which is a significant complication of a parathyroidectomy following chronic hyperparathyroidism. This condition causes hypocalcaemia and is rare but important to recognize. Osteomalacia, rickets, and scurvy are not consistent with this patient’s history and are not the correct answers.
Understanding Hungry Bone Syndrome
Hungry bone syndrome is a rare condition that can occur after a parathyroidectomy, especially if the patient has had hyperparathyroidism for a long time. The condition is caused by high levels of parathyroid hormone before surgery, which stimulate osteoclast activity and lead to demineralization of the bones, resulting in hypercalcemia. If left untreated, this can cause x-ray changes that resemble metastatic lytic lesions.
During the parathyroidectomy, the parathyroid adenoma is removed, causing a rapid drop in hormone levels, which have a short half-life. As a result, osteoclast activity decreases, and the bones begin to rapidly re-mineralize, leading to hungry bone syndrome. This process can be uncomfortable and can also cause systemic hypocalcemia.
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This question is part of the following fields:
- Renal System
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Question 20
Incorrect
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A 6-year-old girl presents with proteinuria, oedema, hypoalbuminaemia, hyperlipidaemia. A diagnosis of nephrotic syndrome secondary to minimal change disease is made.
What is the most suitable medication for treatment in this case?Your Answer:
Correct Answer: Steroids
Explanation:Prednisolone is the optimal treatment for minimal change glomerulonephritis presenting with nephrotic syndrome, while the other medications mentioned are not appropriate options.
Minimal change disease is a condition that typically presents as nephrotic syndrome, with children accounting for 75% of cases and adults accounting for 25%. While most cases are idiopathic, a cause can be found in around 10-20% of cases, such as drugs like NSAIDs and rifampicin, Hodgkin’s lymphoma, thymoma, or infectious mononucleosis. The pathophysiology of the disease involves T-cell and cytokine-mediated damage to the glomerular basement membrane, resulting in polyanion loss and a reduction of electrostatic charge, which increases glomerular permeability to serum albumin.
The features of minimal change disease include nephrotic syndrome, normotension (hypertension is rare), and highly selective proteinuria, where only intermediate-sized proteins like albumin and transferrin leak through the glomerulus. Renal biopsy shows normal glomeruli on light microscopy, while electron microscopy shows fusion of podocytes and effacement of foot processes.
Management of minimal change disease involves oral corticosteroids, which are effective in 80% of cases. For steroid-resistant cases, cyclophosphamide is the next step. The prognosis for the disease is generally good, although relapse is common. Roughly one-third of patients have just one episode, one-third have infrequent relapses, and one-third have frequent relapses that stop before adulthood.
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This question is part of the following fields:
- Renal System
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Question 21
Incorrect
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A 67-year-old retired farmer presents to the emergency department with complaints of abdominal pain and inability to urinate for the past 24 hours. He reports a history of slow urine flow and difficulty emptying his bladder for the past few years. The patient has a medical history of type 2 diabetes mellitus, hypertension, and lower back pain, and underwent surgery for an inguinal hernia 2 years ago. Ultrasound reveals a distended bladder and hydronephrosis, and the patient undergoes urethral catheterization. Further investigation shows an enlarged prostate and an increase in free prostate-specific antigen (PSA), and a prostate biopsy is scheduled. Which part of the prostate is most likely causing bladder obstruction in this patient?
Your Answer:
Correct Answer: Lateral and middle lobe lobe
Explanation:A man presented with symptoms of acute urinary retention and a history of poor urine flow and straining to void, suggesting bladder outlet obstruction possibly due to an enlarged prostate. While prostatic adenocarcinoma is common in men over 50, it is unlikely to cause urinary symptoms. However, patients should still be screened for it to allow for early intervention if necessary. The man’s increased levels of free PSA indicate BPH rather than prostatic adenocarcinoma, as the latter would result in decreased free PSA and increased bound-PSA levels.
The lateral and middle lobes of the prostate are closest to the urethra and their hyperplasia can compress it, leading to urinary and voiding symptoms. If the urethra is completely compressed, acute urinary retention and bladder outlet obstruction can occur. The anterior lobe is rarely enlarged in BPH and is not positioned to obstruct the urethra, while the posterior lobe is mostly involved in prostatic adenocarcinoma but does not typically cause urinary symptoms due to its distance from the urethra.
Benign prostatic hyperplasia (BPH) is a common condition that affects older men, with around 50% of 50-year-old men showing evidence of BPH and 30% experiencing symptoms. The risk of BPH increases with age, with around 80% of 80-year-old men having evidence of the condition. Ethnicity also plays a role, with black men having a higher risk than white or Asian men. BPH typically presents with lower urinary tract symptoms (LUTS), which can be categorised into obstructive (voiding) symptoms and irritative (storage) symptoms. Complications of BPH can include urinary tract infections, retention, and obstructive uropathy.
Assessment of BPH may involve dipstick urine testing, U&Es, and PSA testing if obstructive symptoms are present or if the patient is concerned about prostate cancer. A urinary frequency-volume chart and the International Prostate Symptom Score (IPSS) can also be used to assess the severity of LUTS and their impact on quality of life. Management options for BPH include watchful waiting, alpha-1 antagonists, 5 alpha-reductase inhibitors, combination therapy, and surgery. Alpha-1 antagonists are considered first-line for moderate-to-severe voiding symptoms and can improve symptoms in around 70% of men, but may cause adverse effects such as dizziness and dry mouth. 5 alpha-reductase inhibitors may slow disease progression and reduce prostate volume, but can cause adverse effects such as erectile dysfunction and reduced libido. Combination therapy may be used for bothersome moderate-to-severe voiding symptoms and prostatic enlargement. Antimuscarinic drugs may be tried for persistent storage symptoms. Surgery, such as transurethral resection of the prostate (TURP), may also be an option.
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This question is part of the following fields:
- Renal System
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Question 22
Incorrect
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A 65-year-old woman with chronic kidney failure has been instructed by her nephrologist to adhere to a 'renal diet'. She visits you to gain more knowledge about this.
What is typically recommended to individuals with chronic kidney disease?Your Answer:
Correct Answer: Low potassium diet
Explanation:Dietary Recommendations for Chronic Kidney Disease Patients
Chronic kidney disease patients are recommended to follow a specific diet that is low in protein, phosphate, sodium, and potassium. This dietary advice is given to reduce the strain on the kidneys, as these substances are typically excreted by the kidneys. By limiting the intake of these nutrients, patients can help slow the progression of their kidney disease and manage their symptoms more effectively. It is important for patients to work closely with their healthcare provider or a registered dietitian to ensure they are meeting their nutritional needs while following these dietary restrictions. With proper guidance and adherence to this diet, patients with chronic kidney disease can improve their overall health and quality of life.
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This question is part of the following fields:
- Renal System
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Question 23
Incorrect
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A patient with compromised kidney function is given a new medication that is typically eliminated through renal excretion. What factors might impact the excretion of the medication?
Your Answer:
Correct Answer: Diffusivity across the basement membrane and tubular secretion/reabsorption
Explanation:The clearance of a substance in the kidneys is influenced by two important factors: diffusivity across the basement membrane and tubular secretion/reabsorption. Additionally, the Loop of Henle plays a crucial role in generating a significant osmotic gradient, while the primary function of the collecting duct is to facilitate the reabsorption of water.
The Loop of Henle and its Role in Renal Physiology
The Loop of Henle is a crucial component of the renal system, located in the juxtamedullary nephrons and running deep into the medulla. Approximately 60 litres of water containing 9000 mmol sodium enters the descending limb of the loop of Henle in 24 hours. The osmolarity of fluid changes and is greatest at the tip of the papilla. The thin ascending limb is impermeable to water, but highly permeable to sodium and chloride ions. This loss means that at the beginning of the thick ascending limb the fluid is hypo osmotic compared with adjacent interstitial fluid. In the thick ascending limb, the reabsorption of sodium and chloride ions occurs by both facilitated and passive diffusion pathways. The loops of Henle are co-located with vasa recta, which have similar solute compositions to the surrounding extracellular fluid, preventing the diffusion and subsequent removal of this hypertonic fluid. The energy-dependent reabsorption of sodium and chloride in the thick ascending limb helps to maintain this osmotic gradient. Overall, the Loop of Henle plays a crucial role in regulating the concentration of solutes in the renal system.
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This question is part of the following fields:
- Renal System
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Question 24
Incorrect
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A 40-year-old man arrives at the emergency department with low blood pressure after a car crash. What is the mechanism by which angiotensin II increases the filtration fraction in the kidney?
Your Answer:
Correct Answer: Vasoconstriction of the efferent glomerular arteriole
Explanation:Angiotensin II helps maintain GFR by increasing the filtration fraction through vasoconstriction of the efferent arteriole of the glomerulus. Despite its vasoconstrictive effect on the glomerular arteries, angiotensin II has a greater impact on the efferent arteriole, leading to an increase in glomerular pressure and filtration fraction.
The renin-angiotensin-aldosterone system is a complex system that regulates blood pressure and fluid balance in the body. The adrenal cortex is divided into three zones, each producing different hormones. The zona glomerulosa produces mineralocorticoids, mainly aldosterone, which helps regulate sodium and potassium levels in the body. Renin is an enzyme released by the renal juxtaglomerular cells in response to reduced renal perfusion, hyponatremia, and sympathetic nerve stimulation. It hydrolyses angiotensinogen to form angiotensin I, which is then converted to angiotensin II by angiotensin-converting enzyme in the lungs. Angiotensin II has various actions, including causing vasoconstriction, stimulating thirst, and increasing proximal tubule Na+/H+ activity. It also stimulates aldosterone and ADH release, which causes retention of Na+ in exchange for K+/H+ in the distal tubule.
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This question is part of the following fields:
- Renal System
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Question 25
Incorrect
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A 35-year-old man comes to you with complaints of pedal oedema, frothy urine and decreased urine output. He has no significant medical history. You suspect that the patient's nephrotic syndrome may be caused by a common form of idiopathic glomerulonephritis that affects adults.
What would be the most helpful initial test to confirm this particular diagnosis?Your Answer:
Correct Answer: Anti-phospholipase A2 antibodies
Explanation:Idiopathic membranous glomerulonephritis is believed to be associated with anti-phospholipase A2 antibodies. This condition is a common cause of nephrotic syndrome in adults, and since the patient has no other relevant medical history, an idiopathic cause is likely. To confirm the diagnosis, measuring anti-phospholipase A2 levels is recommended.
Testing for ASOT would suggest post-streptococcal glomerulonephritis (PSGN), which is more common in children and typically presents with an acute nephritic picture rather than nephrotic syndrome. Therefore, this is not the most likely diagnosis.
While dyslipidaemia is commonly found in nephrotic syndrome, confirming it would not help confirm the suspected diagnosis of idiopathic membranous glomerulonephritis.
Although acute kidney injury (AKI) can occur in individuals with nephrotic syndrome, assessing renal function is unlikely to help diagnose membranous glomerulonephritis.
While assessing the protein content in a sample may be useful in diagnosing nephrotic syndrome, it is not specific to membranous glomerulonephritis.
Membranous glomerulonephritis is the most common type of glomerulonephritis in adults and is the third leading cause of end-stage renal failure. It typically presents with proteinuria or nephrotic syndrome. A renal biopsy will show a thickened basement membrane with subepithelial electron dense deposits, creating a spike and dome appearance. The condition can be caused by various factors, including infections, malignancy, drugs, autoimmune diseases, and idiopathic reasons.
Management of membranous glomerulonephritis involves the use of ACE inhibitors or ARBs to reduce proteinuria and improve prognosis. Immunosuppression may be necessary for patients with severe or progressive disease, but many patients spontaneously improve. Corticosteroids alone are not effective, and a combination of corticosteroid and another agent such as cyclophosphamide is often used. Anticoagulation may be considered for high-risk patients.
The prognosis for membranous glomerulonephritis follows the rule of thirds: one-third of patients experience spontaneous remission, one-third remain proteinuric, and one-third develop end-stage renal failure. Good prognostic factors include female sex, young age at presentation, and asymptomatic proteinuria of a modest degree at the time of diagnosis.
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This question is part of the following fields:
- Renal System
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Question 26
Incorrect
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A 75-year-old man has been admitted to the renal ward with acute kidney injury. His blood test reveals low sodium levels and high potassium levels, likely due to his current renal function. You review his medications to ensure they are not exacerbating the situation. Which medication would you contemplate discontinuing due to its link with hyperkalemia?
Your Answer:
Correct Answer: Spironolactone
Explanation:Spironolactone is a diuretic that helps to retain potassium in the body, which can lead to hyperkalaemia. It is important to discontinue its use in patients with hyperkalaemia. Furthermore, it should not be used in cases of acute renal insufficiency.
Salbutamol, on the other hand, does not cause hyperkalaemia. In fact, it can be used to reduce high levels of potassium in severe cases.
Paracetamol, when used as directed, does not have any impact on potassium levels.
Verapamil is a medication that blocks calcium channels and does not affect potassium levels.
Drugs and their Effects on Potassium Levels
Many commonly prescribed drugs have the potential to alter the levels of potassium in the bloodstream. Some drugs can decrease the amount of potassium in the blood, while others can increase it.
Drugs that can decrease serum potassium levels include thiazide and loop diuretics, as well as acetazolamide. On the other hand, drugs that can increase serum potassium levels include ACE inhibitors, angiotensin-2 receptor blockers, spironolactone, and potassium-sparing diuretics like amiloride and triamterene. Additionally, taking potassium supplements like Sando-K or Slow-K can also increase potassium levels in the blood.
It’s important to note that the above list does not include drugs used to temporarily decrease serum potassium levels for patients with hyperkalaemia, such as salbutamol or calcium resonium.
Overall, it’s crucial for healthcare providers to be aware of the potential effects of medications on potassium levels and to monitor patients accordingly.
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This question is part of the following fields:
- Renal System
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Question 27
Incorrect
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John, 72-years-old, visits his GP with concerns of frequent urination accompanied by a burning sensation and interrupted flow of urine that have persisted for approximately 5 months. During a digital rectal examination, an enlarged, nodular prostate is detected and his PSA levels are significantly elevated. Following a biopsy, he is diagnosed with prostate cancer. Which zone of the prostate is commonly affected by prostate cancer and experiences enlargement?
Your Answer:
Correct Answer: Peripheral zone
Explanation:Prostate cancer is a common condition with up to 30,000 men diagnosed and 9,000 deaths per year in the UK. Diagnosis involves PSA measurement, digital rectal examination, and imaging for staging. Pathology shows 95% adenocarcinoma, often multifocal and graded using the Gleason system. Treatment options include watchful waiting, radiotherapy, surgery, and hormonal therapy. Active surveillance is recommended for low-risk men, with treatment decisions made based on disease progression and individual factors.
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This question is part of the following fields:
- Renal System
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Question 28
Incorrect
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A 26-year-old man has been in a car accident and his right leg has been trapped for 5 hours during transportation. During examination, his foot is found to be insensate and there is only a weakly felt dorsalis pedis pulse. Which of the following biochemical abnormalities is most likely to be present?
Your Answer:
Correct Answer: Hyperkalaemia
Explanation:The patient is expected to suffer from compartment syndrome, which may lead to delayed diagnosis and muscle necrosis. Muscle necrosis can cause the release of potassium, and there is a high probability of renal dysfunction, which can result in elevated serum potassium levels.
Hyperkalaemia is a condition where there is an excess of potassium in the blood. The levels of potassium in the plasma are regulated by various factors such as aldosterone, insulin levels, and acid-base balance. When there is metabolic acidosis, hyperkalaemia can occur as hydrogen and potassium ions compete with each other for exchange with sodium ions across cell membranes and in the distal tubule. The ECG changes that can be seen in hyperkalaemia include tall-tented T waves, small P waves, widened QRS leading to a sinusoidal pattern, and asystole.
There are several causes of hyperkalaemia, including acute kidney injury, drugs such as potassium sparing diuretics, ACE inhibitors, angiotensin 2 receptor blockers, spironolactone, ciclosporin, and heparin, metabolic acidosis, Addison’s disease, rhabdomyolysis, and massive blood transfusion. Foods that are high in potassium include salt substitutes, bananas, oranges, kiwi fruit, avocado, spinach, and tomatoes.
It is important to note that beta-blockers can interfere with potassium transport into cells and potentially cause hyperkalaemia in renal failure patients. In contrast, beta-agonists such as Salbutamol are sometimes used as emergency treatment. Additionally, both unfractionated and low-molecular weight heparin can cause hyperkalaemia by inhibiting aldosterone secretion.
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This question is part of the following fields:
- Renal System
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Question 29
Incorrect
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An elderly man of 74 years old complains of symptoms and displays signs of benign prostatic hyperplasia. Which structure is most likely to be enlarged in his case?
Your Answer:
Correct Answer: Median lobe of the prostate
Explanation:Prostate carcinoma commonly develops in the posterior lobe, while BPH often causes enlargement of the median lobe. The anterior lobe, which contains minimal glandular tissue, is rarely affected by enlargement.
Benign prostatic hyperplasia (BPH) is a common condition that affects older men, with around 50% of 50-year-old men showing evidence of BPH and 30% experiencing symptoms. The risk of BPH increases with age, with around 80% of 80-year-old men having evidence of the condition. Ethnicity also plays a role, with black men having a higher risk than white or Asian men. BPH typically presents with lower urinary tract symptoms (LUTS), which can be categorised into obstructive (voiding) symptoms and irritative (storage) symptoms. Complications of BPH can include urinary tract infections, retention, and obstructive uropathy.
Assessment of BPH may involve dipstick urine testing, U&Es, and PSA testing if obstructive symptoms are present or if the patient is concerned about prostate cancer. A urinary frequency-volume chart and the International Prostate Symptom Score (IPSS) can also be used to assess the severity of LUTS and their impact on quality of life. Management options for BPH include watchful waiting, alpha-1 antagonists, 5 alpha-reductase inhibitors, combination therapy, and surgery. Alpha-1 antagonists are considered first-line for moderate-to-severe voiding symptoms and can improve symptoms in around 70% of men, but may cause adverse effects such as dizziness and dry mouth. 5 alpha-reductase inhibitors may slow disease progression and reduce prostate volume, but can cause adverse effects such as erectile dysfunction and reduced libido. Combination therapy may be used for bothersome moderate-to-severe voiding symptoms and prostatic enlargement. Antimuscarinic drugs may be tried for persistent storage symptoms. Surgery, such as transurethral resection of the prostate (TURP), may also be an option.
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This question is part of the following fields:
- Renal System
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Question 30
Incorrect
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A 73-year-old man visits the urology clinic due to an elevated PSA level. Despite undergoing a biopsy, there are no indications of cancer or benign prostatic hypertrophy.
The patient has a medical history of diabetes mellitus, hypertension, scrotal varicocele, renal calculi, and acute urine retention.
Out of his existing medical conditions, which one is the probable culprit for his increased PSA level?Your Answer:
Correct Answer: Urine retention
Explanation:Urinary retention is a common cause of a raised PSA reading, as it can lead to bladder enlargement. Other conditions such as diabetes mellitus, hypertension, and renal calculi are not direct causes of elevated PSA levels.
Understanding PSA Testing for Prostate Cancer
Prostate specific antigen (PSA) is an enzyme produced by the prostate gland that has become an important marker for prostate cancer. However, there is still much debate about its usefulness as a screening tool. The NHS Prostate Cancer Risk Management Programme (PCRMP) has published guidelines on how to handle requests for PSA testing in asymptomatic men. While a recent European trial showed a reduction in prostate cancer deaths, there is also a high risk of over-diagnosis and over-treatment. As a result, the National Screening Committee has decided not to introduce a prostate cancer screening programme yet, but rather allow men to make an informed choice.
PSA levels may be raised by various factors, including benign prostatic hyperplasia, prostatitis, ejaculation, vigorous exercise, urinary retention, and instrumentation of the urinary tract. However, PSA levels are not always a reliable indicator of prostate cancer. For example, around 20% of men with prostate cancer have a normal PSA level, while around 33% of men with a PSA level of 4-10 ng/ml will be found to have prostate cancer. To add greater meaning to a PSA level, age-adjusted upper limits and monitoring changes in PSA level over time (PSA velocity or PSA doubling time) are used. The PCRMP recommends age-adjusted upper limits for PSA levels, with a limit of 3.0 ng/ml for men aged 50-59 years, 4.0 ng/ml for men aged 60-69 years, and 5.0 ng/ml for men over 70 years old.
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This question is part of the following fields:
- Renal System
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Question 31
Incorrect
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A 6-year-old boy arrives at the paediatric emergency department with a non-blanching rash. He is limping and complaining of abdominal pain. He had a recent bout of tonsillitis but is typically healthy. Upon examination, there are numerous palpable purpura in a symmetrical pattern, mainly on his buttocks and the backs of his legs. A urine dipstick reveals mild proteinuria and 2+ blood.
What is the probable underlying pathophysiology of this presentation?Your Answer:
Correct Answer: IgA mediated small vessel vasculitis
Explanation:The correct answer is IgA mediated small vessel vasculitis, specifically Henoch-Schonlein purpura (HSP). This condition is characterized by palpable purpura, arthralgia, abdominal pain, and haematuria, and typically affects children aged 4-6 years. HSP is often triggered by infections such as streptococcal pharyngitis, but can also be caused by other infections like Mycoplasma pneumoniae, Epstein-Barr virus, and adenovirus.
The other options are incorrect. ANCA-associated vasculitis typically involves the respiratory and ENT systems, which this child does not have. Cryoglobulinaemic vasculitis is associated with hepatitis C, haematological malignancies, and autoimmune disease, none of which are present in this case. Deficiency of von Willebrand factor cleaving protein is a feature of TTP, which is rare in children and typically presents with a low platelet count. ITP is another autoimmune condition that can present similarly to HSP, but can be differentiated by a low platelet count.
Understanding Henoch-Schonlein Purpura
Henoch-Schonlein purpura (HSP) is a type of small vessel vasculitis that is mediated by IgA. It is often associated with IgA nephropathy, also known as Berger’s disease. HSP is commonly observed in children following an infection.
The condition is characterized by a palpable purpuric rash, which is accompanied by localized oedema over the buttocks and extensor surfaces of the arms and legs. Other symptoms include abdominal pain and polyarthritis. In some cases, patients may also experience haematuria and renal failure, which are indicative of IgA nephropathy.
Treatment for HSP typically involves analgesia for arthralgia. While there is inconsistent evidence for the use of steroids and immunosuppressants, supportive care is generally recommended for patients with nephropathy. The prognosis for HSP is usually excellent, particularly in children without renal involvement. However, it is important to monitor blood pressure and urinalysis to detect any signs of progressive renal involvement. Approximately one-third of patients may experience a relapse.
In summary, Henoch-Schonlein purpura is a self-limiting condition that is often seen in children following an infection. While the symptoms can be uncomfortable, the prognosis is generally good. However, it is important to monitor patients for any signs of renal involvement and provide appropriate supportive care.
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This question is part of the following fields:
- Renal System
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Question 32
Incorrect
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A 35-year-old man with end-stage renal failure due to polycystic kidney disease is being evaluated for a possible kidney transplant. Donor screening, which involves human leukocyte antigen (HLA) testing, has been conducted on several family members. Which HLA class is the most crucial in minimizing rejection risk for this patient?
Your Answer:
Correct Answer: DR
Explanation:The HLA system, also known as the major histocompatibility complex (MHC), is located on chromosome 6 and is responsible for human leucocyte antigens. Class 1 antigens include A, B, and C, while class 2 antigens include DP, DQ, and DR. When matching for a renal transplant, the importance of HLA antigens is ranked as DR > B > A.
Graft survival rates for renal transplants are high, with a 90% survival rate at one year and a 60% survival rate at ten years for cadaveric transplants. Living-donor transplants have even higher survival rates, with a 95% survival rate at one year and a 70% survival rate at ten years. However, postoperative problems can occur, such as acute tubular necrosis of the graft, vascular thrombosis, urine leakage, and urinary tract infections.
Hyperacute rejection can occur within minutes to hours after a transplant and is caused by pre-existing antibodies against ABO or HLA antigens. This type of rejection is an example of a type II hypersensitivity reaction and leads to widespread thrombosis of graft vessels, resulting in ischemia and necrosis of the transplanted organ. Unfortunately, there is no treatment available for hyperacute rejection, and the graft must be removed.
Acute graft failure, which occurs within six months of a transplant, is usually due to mismatched HLA and is caused by cell-mediated cytotoxic T cells. This type of failure is usually asymptomatic and is detected by a rising creatinine, pyuria, and proteinuria. Other causes of acute graft failure include cytomegalovirus infection, but it may be reversible with steroids and immunosuppressants.
Chronic graft failure, which occurs after six months of a transplant, is caused by both antibody and cell-mediated mechanisms that lead to fibrosis of the transplanted kidney, known as chronic allograft nephropathy. The recurrence of the original renal disease, such as MCGN, IgA, or FSGS, can also cause chronic graft failure.
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This question is part of the following fields:
- Renal System
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Question 33
Incorrect
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A 67-year-old man is attending the urology clinic and receiving goserelin for his metastatic prostate cancer. Can you explain the drug's mechanism of action?
Your Answer:
Correct Answer: Overstimulation of GnRH receptors
Explanation:GnRH agonists used in the treatment of prostate cancer can paradoxically lead to lower LH levels in the long term. This is because chronic use of these agonists can result in overstimulation of GnRH receptors, which in turn disrupts endogenous hormonal feedback systems. While initially stimulating the production of LH/FSH and subsequent androgen production, chronic use of GnRH agonists can cause negative feedback to suppress the release of gonadotropins, resulting in a significant decrease in serum testosterone levels. This mechanism can be thought of as switching on to switch off. It is important to note that inhibiting the 5 alpha-reductase enzyme and relaxing prostatic smooth muscle are not mechanisms of action for GnRH agonists, but rather for other medications used in the treatment of prostate conditions.
Prostate cancer management varies depending on the stage of the disease and the patient’s life expectancy and preferences. For localized prostate cancer (T1/T2), treatment options include active monitoring, watchful waiting, radical prostatectomy, and radiotherapy (external beam and brachytherapy). For localized advanced prostate cancer (T3/T4), options include hormonal therapy, radical prostatectomy, and radiotherapy. Patients may develop proctitis and are at increased risk of bladder, colon, and rectal cancer following radiotherapy for prostate cancer.
In cases of metastatic prostate cancer, reducing androgen levels is a key aim of treatment. A combination of approaches is often used, including anti-androgen therapy, synthetic GnRH agonist or antagonists, bicalutamide, cyproterone acetate, abiraterone, and bilateral orchidectomy. GnRH agonists, such as Goserelin (Zoladex), initially cause a rise in testosterone levels before falling to castration levels. To prevent a rise in testosterone, anti-androgens are often used to cover the initial therapy. GnRH antagonists, such as degarelix, are being evaluated to suppress testosterone while avoiding the flare phenomenon. Chemotherapy with docetaxel is also an option for the treatment of hormone-relapsed metastatic prostate cancer in patients who have no or mild symptoms after androgen deprivation therapy has failed, and before chemotherapy is indicated.
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This question is part of the following fields:
- Renal System
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Question 34
Incorrect
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A 42-year-old man is admitted to the gastroenterology ward with a flare-up of his Crohn's disease. He has been experiencing up to 6 bowel movements per day for the past 2 weeks and has lost around 5kg in weight.
What are the expected biochemical abnormalities in this clinical scenario?Your Answer:
Correct Answer: Metabolic acidosis, normal anion gap, hypokalaemia
Explanation:Prolonged diarrhoea can lead to a normal anion gap metabolic acidosis and hypokalaemia. This is due to the loss of potassium and other electrolytes through the gastrointestinal tract. The anion gap remains within normal limits despite the metabolic acidosis caused by diarrhoea. It is important to monitor electrolyte levels in patients with prolonged diarrhoea to prevent complications.
Understanding Metabolic Acidosis
Metabolic acidosis is a condition that can be classified based on the anion gap, which is calculated by subtracting the sum of chloride and bicarbonate from the sum of sodium and potassium. The normal range for anion gap is 10-18 mmol/L. If a question provides the chloride level, it may be an indication to calculate the anion gap.
Hyperchloraemic metabolic acidosis is a type of metabolic acidosis with a normal anion gap. It can be caused by gastrointestinal bicarbonate loss, prolonged diarrhea, ureterosigmoidostomy, fistula, renal tubular acidosis, drugs like acetazolamide, ammonium chloride injection, and Addison’s disease. On the other hand, raised anion gap metabolic acidosis is caused by lactate, ketones, urate, acid poisoning, and other factors.
Lactic acidosis is a type of metabolic acidosis that is caused by high lactate levels. It can be further classified into two types: lactic acidosis type A, which is caused by sepsis, shock, hypoxia, and burns, and lactic acidosis type B, which is caused by metformin. Understanding the different types and causes of metabolic acidosis is important in diagnosing and treating the condition.
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This question is part of the following fields:
- Renal System
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Question 35
Incorrect
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A 69-year-old man is admitted to the medical assessment unit with reduced urine output and nausea. He has a complex medical history, including heart failure, hypercholesterolemia, hypertension, type 1 diabetes mellitus, and hypothyroidism. Among his regular medications are bisoprolol, furosemide, simvastatin, insulin, and levothyroxine. The medical team suspects that he is currently experiencing an acute kidney injury.
Which of his usual medications should be discontinued?Your Answer:
Correct Answer: Furosemide
Explanation:In cases of AKI, it is advisable to discontinue the use of diuretics as they may aggravate renal function. Loop diuretics like Furosemide should be stopped. Additionally, drugs that have the potential to harm the kidneys, such as aminoglycoside antibiotics (e.g. gentamicin), non-steroidal anti-inflammatory drugs, angiotensin-converting enzyme inhibitors (e.g. ramipril), angiotensin II receptor antagonists (e.g. losartan), and diuretics, should also be discontinued.
Fortunately, the remaining drugs are generally safe to continue as they are not typically considered nephrotoxic. Insulin, a peptide hormone drug used in treating type 1 and type 2 diabetes mellitus, is cleared from the body through enzymatic breakdown in the liver and kidneys and is not usually harmful to the kidneys.
Acute kidney injury (AKI) is a condition where there is a reduction in renal function following an insult to the kidneys. It was previously known as acute renal failure and can result in long-term impaired kidney function or even death. AKI can be caused by prerenal, intrinsic, or postrenal factors. Patients with chronic kidney disease, other organ failure/chronic disease, a history of AKI, or who have used drugs with nephrotoxic potential are at an increased risk of developing AKI. To prevent AKI, patients at risk may be given IV fluids or have certain medications temporarily stopped.
The kidneys are responsible for maintaining fluid balance and homeostasis, so a reduced urine output or fluid overload may indicate AKI. Symptoms may not be present in early stages, but as renal failure progresses, patients may experience arrhythmias, pulmonary and peripheral edema, or features of uraemia. Blood tests such as urea and electrolytes can be used to detect AKI, and urinalysis and imaging may also be necessary.
Management of AKI is largely supportive, with careful fluid balance and medication review. Loop diuretics and low-dose dopamine are not recommended, but hyperkalaemia needs prompt treatment to avoid life-threatening arrhythmias. Renal replacement therapy may be necessary in severe cases. Patients with suspected AKI secondary to urinary obstruction require prompt review by a urologist, and specialist input from a nephrologist is required for cases where the cause is unknown or the AKI is severe.
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This question is part of the following fields:
- Renal System
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Question 36
Incorrect
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A 63-year-old man is seen in the oncology clinic. He is being monitored for known breast cancer. His recent mammogram and biopsy suggest an increased disease burden. It is decided to initiate Tamoxifen therapy while awaiting a mastectomy.
What is the mechanism of action of this new medication?Your Answer:
Correct Answer: Androgen receptor blocker
Explanation:Bicalutamide is a medication that blocks the androgen receptor and is commonly used to treat prostate cancer. Abiraterone, on the other hand, is an androgen synthesis inhibitor that is prescribed to patients with metastatic prostate cancer who have not responded to androgen deprivation therapy. GnRH agonists like goserelin can also be used to treat prostate cancer by reducing the release of gonadotrophins and inhibiting androgen production. While cyproterone acetate is a steroidal anti-androgen, it is not as commonly used as non-steroidal anti-androgens like bicalutamide.
Prostate cancer management varies depending on the stage of the disease and the patient’s life expectancy and preferences. For localized prostate cancer (T1/T2), treatment options include active monitoring, watchful waiting, radical prostatectomy, and radiotherapy (external beam and brachytherapy). For localized advanced prostate cancer (T3/T4), options include hormonal therapy, radical prostatectomy, and radiotherapy. Patients may develop proctitis and are at increased risk of bladder, colon, and rectal cancer following radiotherapy for prostate cancer.
In cases of metastatic prostate cancer, reducing androgen levels is a key aim of treatment. A combination of approaches is often used, including anti-androgen therapy, synthetic GnRH agonist or antagonists, bicalutamide, cyproterone acetate, abiraterone, and bilateral orchidectomy. GnRH agonists, such as Goserelin (Zoladex), initially cause a rise in testosterone levels before falling to castration levels. To prevent a rise in testosterone, anti-androgens are often used to cover the initial therapy. GnRH antagonists, such as degarelix, are being evaluated to suppress testosterone while avoiding the flare phenomenon. Chemotherapy with docetaxel is also an option for the treatment of hormone-relapsed metastatic prostate cancer in patients who have no or mild symptoms after androgen deprivation therapy has failed, and before chemotherapy is indicated.
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This question is part of the following fields:
- Renal System
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Question 37
Incorrect
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A 67-year-old man presents with hypertension and a history of angina and peripheral vascular disease. During the physical examination, you detect a renal bruit on the left side. What is the most effective approach to evaluate renal blood flow in this individual?
Your Answer:
Correct Answer: Para-aminohippurate (PAH) clearance
Explanation:Renal artery stenosis is the likely diagnosis for the patient, as it causes a reduction in renal blood flow. To measure renal plasma flow, the gold standard method in renal physiology is the use of para-aminohippurate (PAH) clearance.
Inulin is an ideal substance for measuring creatinine clearance (CrCl) as it is completely filtered at the glomerulus and not secreted or reabsorbed by the tubules. The Modification of Diet in Renal Disease (MDRD) and Cockcroft-Gault equation are commonly used to estimate creatinine clearance.
Reabsorption and Secretion in Renal Function
In renal function, reabsorption and secretion play important roles in maintaining homeostasis. The filtered load is the amount of a substance that is filtered by the glomerulus and is determined by the glomerular filtration rate (GFR) and the plasma concentration of the substance. The excretion rate is the amount of the substance that is eliminated in the urine and is determined by the urine flow rate and the urine concentration of the substance. Reabsorption occurs when the filtered load is greater than the excretion rate, and secretion occurs when the excretion rate is greater than the filtered load.
The reabsorption rate is the difference between the filtered load and the excretion rate, and the secretion rate is the difference between the excretion rate and the filtered load. Reabsorption and secretion can occur in different parts of the nephron, including the proximal tubule, loop of Henle, distal tubule, and collecting duct. These processes are regulated by various hormones and signaling pathways, such as aldosterone, antidiuretic hormone (ADH), and atrial natriuretic peptide (ANP).
Overall, reabsorption and secretion are important mechanisms for regulating the composition of the urine and maintaining fluid and electrolyte balance in the body. Dysfunction of these processes can lead to various renal disorders, such as diabetes insipidus, renal tubular acidosis, and Fanconi syndrome.
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This question is part of the following fields:
- Renal System
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Question 38
Incorrect
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A 60-year-old man complains of excessive urination and increased thirst. You want to examine for diabetes insipidus.
What is the most suitable test to conduct?Your Answer:
Correct Answer: Water deprivation test
Explanation:The water deprivation test is a diagnostic tool for investigating diabetes insipidus. The Short Synacthen test is utilized to diagnose Addison’s disease. Cranial diabetes insipidus can be treated with Desmopressin, while nephrogenic diabetes insipidus can be treated with thiazide diuretics.
Diabetes insipidus is a medical condition that can be caused by either a decreased secretion of antidiuretic hormone (ADH) from the pituitary gland (cranial DI) or an insensitivity to ADH (nephrogenic DI). Cranial DI can be caused by various factors such as head injury, pituitary surgery, and infiltrative diseases like sarcoidosis. On the other hand, nephrogenic DI can be caused by genetic factors, electrolyte imbalances, and certain medications like lithium and demeclocycline. The common symptoms of DI are excessive urination and thirst. Diagnosis is made through a water deprivation test and checking the osmolality of the urine. Treatment options include thiazides and a low salt/protein diet for nephrogenic DI, while central DI can be treated with desmopressin.
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This question is part of the following fields:
- Renal System
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Question 39
Incorrect
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A 65-year-old man is undergoing assessment for polycythemia and has no history of smoking. What type of solid-organ cancer could be a possible cause?
Your Answer:
Correct Answer: Renal cell carcinoma
Explanation:Renal cell carcinoma has the potential to secrete various hormones such as erythropoietin, PTHrP, renin, or ACTH. This can lead to secondary polycythemia, hypercalcemia, or other related conditions. On the other hand, small cell lung cancer can cause ectopic secretion of ACTH or ADH, but not erythropoietin. Pituitary tumors, on the other hand, may secrete prolactin.
Renal cell cancer, also known as hypernephroma, is a primary renal neoplasm that accounts for 85% of cases. It originates from the proximal renal tubular epithelium and is commonly associated with smoking and conditions such as von Hippel-Lindau syndrome and tuberous sclerosis. The clear cell subtype is the most prevalent, comprising 75-85% of tumors.
Renal cell cancer is more common in middle-aged men and may present with classical symptoms such as haematuria, loin pain, and an abdominal mass. Other features include endocrine effects, such as the secretion of erythropoietin, parathyroid hormone-related protein, renin, and ACTH. Metastases are present in 25% of cases at presentation, and paraneoplastic syndromes such as Stauffer syndrome may also occur.
The T category criteria for renal cell cancer are based on tumor size and extent of invasion. Management options include partial or total nephrectomy, depending on the tumor size and extent of disease. Patients with a T1 tumor are typically offered a partial nephrectomy, while alpha-interferon and interleukin-2 may be used to reduce tumor size and treat metastases. Receptor tyrosine kinase inhibitors such as sorafenib and sunitinib have shown superior efficacy compared to interferon-alpha.
In summary, renal cell cancer is a common primary renal neoplasm that is associated with various risk factors and may present with classical symptoms and endocrine effects. Management options depend on the extent of disease and may include surgery and targeted therapies.
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This question is part of the following fields:
- Renal System
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Question 40
Incorrect
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A 70-year-old woman with bilateral pitting edema that extends above the knee is prescribed furosemide. What is the mechanism of action of this medication?
Your Answer:
Correct Answer: Inhibits the sodium-potassium-chloride cotransporter
Explanation:Furosemide is a type of loop diuretic that works by inhibiting the cotransporter in the thick ascending loop of Henle, which prevents the reabsorption of sodium, chloride, and potassium. This results in significant diuresis.
Mannitol is an osmotic diuretic that is commonly used to reduce intracranial pressure after a head injury. Spironolactone is an aldosterone antagonist, while bendroflumethiazide acts on the sodium-chloride transporter in the distal convoluted tubule. Acetazolamide is a carbonic anhydrase inhibitor that is often prescribed for the treatment of acute angle closure glaucoma.
Diuretic drugs are classified into three major categories based on the location where they inhibit sodium reabsorption. Loop diuretics act on the thick ascending loop of Henle, thiazide diuretics on the distal tubule and connecting segment, and potassium sparing diuretics on the aldosterone-sensitive principal cells in the cortical collecting tubule. Sodium is reabsorbed in the kidney through Na+/K+ ATPase pumps located on the basolateral membrane, which return reabsorbed sodium to the circulation and maintain low intracellular sodium levels. This ensures a constant concentration gradient.
The physiological effects of commonly used diuretics vary based on their site of action. furosemide, a loop diuretic, inhibits the Na+/K+/2Cl- carrier in the ascending limb of the loop of Henle and can result in up to 25% of filtered sodium being excreted. Thiazide diuretics, which act on the distal tubule and connecting segment, inhibit the Na+Cl- carrier and typically result in between 3 and 5% of filtered sodium being excreted. Finally, spironolactone, a potassium sparing diuretic, inhibits the Na+/K+ ATPase pump in the cortical collecting tubule and typically results in between 1 and 2% of filtered sodium being excreted.
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This question is part of the following fields:
- Renal System
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Question 41
Incorrect
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A 65-year-old man has been prescribed dapagliflozin by his physician to improve management of his pre-existing type 2 diabetes mellitus following a raised HbA1c reading.
What is the main site of action for this medication?Your Answer:
Correct Answer: Renal proximal convoluted tubule
Explanation:The proximal convoluted tubule in the nephron is responsible for the majority of glucose reabsorption. Dapagliflozin, a sodium-glucose co-transporter 2 (SGLT-2) inhibitor, acts on this area to reduce glucose reabsorption, resulting in glycosuria. While this can aid in glycaemic control and weight loss, it also increases the risk of urinary tract infections. Other SGLT-2 inhibitors include canagliflozin and empagliflozin. The distal convoluted tubule is important for ion absorption, while the cortical collecting duct regulates water reabsorption. Sulfonylureas act on pancreatic beta cells, not acinar cells, which are responsible for exocrine function and are not targeted by SGLT-2 inhibitors.
The Loop of Henle and its Role in Renal Physiology
The Loop of Henle is a crucial component of the renal system, located in the juxtamedullary nephrons and running deep into the medulla. Approximately 60 litres of water containing 9000 mmol sodium enters the descending limb of the loop of Henle in 24 hours. The osmolarity of fluid changes and is greatest at the tip of the papilla. The thin ascending limb is impermeable to water, but highly permeable to sodium and chloride ions. This loss means that at the beginning of the thick ascending limb the fluid is hypo osmotic compared with adjacent interstitial fluid. In the thick ascending limb, the reabsorption of sodium and chloride ions occurs by both facilitated and passive diffusion pathways. The loops of Henle are co-located with vasa recta, which have similar solute compositions to the surrounding extracellular fluid, preventing the diffusion and subsequent removal of this hypertonic fluid. The energy-dependent reabsorption of sodium and chloride in the thick ascending limb helps to maintain this osmotic gradient. Overall, the Loop of Henle plays a crucial role in regulating the concentration of solutes in the renal system.
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This question is part of the following fields:
- Renal System
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Question 42
Incorrect
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A 65-year-old woman visits her GP after experiencing painless frank haematuria. She reports that this happened two days ago and her urine looked like port wine. She has a smoking history of 30 pack-years and denies drinking alcohol.
The patient is urgently referred for cystoscopy, which reveals a 2x3cm ulcerated lesion adjacent to the left ureteric orifice. The lesion is biopsied and diagnosed as transitional cell carcinoma.
Which venous structure transmits blood from the tumour to the internal iliac veins?Your Answer:
Correct Answer: Vesicouterine plexus
Explanation:The vesicouterine plexus is responsible for draining the bladder in females.
Bladder Anatomy and Innervation
The bladder is a three-sided pyramid-shaped organ located in the pelvic cavity. Its apex points towards the symphysis pubis, while the base lies anterior to the rectum or vagina. The bladder’s inferior aspect is retroperitoneal, while the superior aspect is covered by peritoneum. The trigone, the least mobile part of the bladder, contains the ureteric orifices and internal urethral orifice. The bladder’s blood supply comes from the superior and inferior vesical arteries, while venous drainage occurs through the vesicoprostatic or vesicouterine venous plexus. Lymphatic drainage occurs mainly to the external iliac and internal iliac nodes, with the obturator nodes also playing a role. The bladder is innervated by parasympathetic nerve fibers from the pelvic splanchnic nerves and sympathetic nerve fibers from L1 and L2 via the hypogastric nerve plexuses. The parasympathetic fibers cause detrusor muscle contraction, while the sympathetic fibers innervate the trigone muscle. The external urethral sphincter is under conscious control, and voiding occurs when the rate of neuronal firing to the detrusor muscle increases.
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This question is part of the following fields:
- Renal System
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Question 43
Incorrect
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A 44-year-old man presents with a three-week history of leg swelling. He has no past medical history except for a bout of sore throat at the age of 15. He is not on any medications. On examination, his blood pressure is 155/94 mmHg, and he has pitting edema. Urinalysis reveals 4+ protein with no RBC casts. A biopsy confirms the diagnosis of membranous glomerulonephritis.
What is the most probable cause of this patient's condition?Your Answer:
Correct Answer: Anti-phospholipase A2 antibodies
Explanation:The likely diagnosis for this patient is idiopathic membranous glomerulonephritis, which is associated with anti-phospholipase A2 antibodies. While hypertension may be present in patients with nephrotic syndrome, it is not the cause of membranous glomerulonephritis. Secondary causes of membranous glomerulonephritis include malignancy (such as lung cancer, lymphoma, or leukemia) and systemic lupus erythematosus, but there are no indications of these in this patient. Sore throat is associated with post-streptococcal glomerulonephritis and IgA nephropathy, but these are not relevant to this case.
Membranous glomerulonephritis is the most common type of glomerulonephritis in adults and is the third leading cause of end-stage renal failure. It typically presents with proteinuria or nephrotic syndrome. A renal biopsy will show a thickened basement membrane with subepithelial electron dense deposits, creating a spike and dome appearance. The condition can be caused by various factors, including infections, malignancy, drugs, autoimmune diseases, and idiopathic reasons.
Management of membranous glomerulonephritis involves the use of ACE inhibitors or ARBs to reduce proteinuria and improve prognosis. Immunosuppression may be necessary for patients with severe or progressive disease, but many patients spontaneously improve. Corticosteroids alone are not effective, and a combination of corticosteroid and another agent such as cyclophosphamide is often used. Anticoagulation may be considered for high-risk patients.
The prognosis for membranous glomerulonephritis follows the rule of thirds: one-third of patients experience spontaneous remission, one-third remain proteinuric, and one-third develop end-stage renal failure. Good prognostic factors include female sex, young age at presentation, and asymptomatic proteinuria of a modest degree at the time of diagnosis.
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This question is part of the following fields:
- Renal System
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Question 44
Incorrect
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A 55-year-old woman who underwent laparoscopic cholecystectomy is being evaluated on postoperative day 2. She reports multiple episodes of vomiting and passing urine only once since the operation. Her medical history includes poorly controlled hypertension on dual therapy. She is currently taking fenoldopam, ACE inhibitors, calcium channel blockers, atorvastatin, and paracetamol. On physical examination, she has dry mucous membranes and a BMI of 31 kg/m². Her vital signs show a mean arterial pressure of 80 mmHg and a heart rate of 110 beats per minute. Laboratory results reveal:
Na+ 130 mmol/L (135 - 145)
K+ 5.1 mmol/L (3.5 - 5.0)
Creatinine 160 µmol/L (55 - 120)
What is the most important medication that should be discontinued in this patient?Your Answer:
Correct Answer: ACE inhibitors
Explanation:In cases of acute kidney injury (AKI), it is crucial to identify and treat the underlying cause. However, it is important to note that ACE inhibitors should be discontinued as they can worsen renal function by causing efferent arteriolar vasodilation, leading to a decrease in GFR. On the other hand, atorvastatin should not be stopped as it does not accumulate and worsen renal function, but frequent monitoring is necessary. If AKI is caused by rhabdomyolysis, then statins should be immediately discontinued. Calcium channel blockers do not exacerbate renal impairment, but it is advisable to reduce the dose and withhold them if clinical signs appear. Fenoldopam, on the other hand, does not impair kidney function but rather increases blood flow to the renal cortex and medullary regions by decreasing systemic vascular resistance.
Acute kidney injury (AKI) is a condition where there is a reduction in renal function following an insult to the kidneys. It was previously known as acute renal failure and can result in long-term impaired kidney function or even death. AKI can be caused by prerenal, intrinsic, or postrenal factors. Patients with chronic kidney disease, other organ failure/chronic disease, a history of AKI, or who have used drugs with nephrotoxic potential are at an increased risk of developing AKI. To prevent AKI, patients at risk may be given IV fluids or have certain medications temporarily stopped.
The kidneys are responsible for maintaining fluid balance and homeostasis, so a reduced urine output or fluid overload may indicate AKI. Symptoms may not be present in early stages, but as renal failure progresses, patients may experience arrhythmias, pulmonary and peripheral edema, or features of uraemia. Blood tests such as urea and electrolytes can be used to detect AKI, and urinalysis and imaging may also be necessary.
Management of AKI is largely supportive, with careful fluid balance and medication review. Loop diuretics and low-dose dopamine are not recommended, but hyperkalaemia needs prompt treatment to avoid life-threatening arrhythmias. Renal replacement therapy may be necessary in severe cases. Patients with suspected AKI secondary to urinary obstruction require prompt review by a urologist, and specialist input from a nephrologist is required for cases where the cause is unknown or the AKI is severe.
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This question is part of the following fields:
- Renal System
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Question 45
Incorrect
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An 80-year-old man visits his GP for a follow up appointment after starting trimethoprim for a urinary tract infection 7 days ago. He mentions that his urinary symptoms have gone but that he has been feeling generally tired and weak for the last 4 weeks (before the urinary tract infection). He asks if this could be related to the new medication he started 5 weeks ago. Upon reviewing his medical history, you see that he was started on ramipril 5 weeks ago. He also mentions that his osteoarthritic pain has been quite bad recently, which caused him to miss his most recent medication review appointment, but he has been taking more paracetamol and ibuprofen than usual. Due to the combination of medication and his vague symptoms, you decide to perform an ECG. The ECG shows tall, tented T waves, prolonged PR interval, and bradycardia. What is the underlying cause of these ECG changes?
Your Answer:
Correct Answer: Hyperkalaemia
Explanation:The patient is most likely suffering from hyperkalaemia, as evidenced by their medication history which includes an increase in potassium-raising drugs such as trimethoprim, ramipril, and ibuprofen. The ECG results also show classic signs of hyperkalaemia, including tall tented T waves, bradycardia, and a prolonged PR interval.
Hyperkalaemia is a condition where there is an excess of potassium in the blood. The levels of potassium in the plasma are regulated by various factors such as aldosterone, insulin levels, and acid-base balance. When there is metabolic acidosis, hyperkalaemia can occur as hydrogen and potassium ions compete with each other for exchange with sodium ions across cell membranes and in the distal tubule. The ECG changes that can be seen in hyperkalaemia include tall-tented T waves, small P waves, widened QRS leading to a sinusoidal pattern, and asystole.
There are several causes of hyperkalaemia, including acute kidney injury, drugs such as potassium sparing diuretics, ACE inhibitors, angiotensin 2 receptor blockers, spironolactone, ciclosporin, and heparin, metabolic acidosis, Addison’s disease, rhabdomyolysis, and massive blood transfusion. Foods that are high in potassium include salt substitutes, bananas, oranges, kiwi fruit, avocado, spinach, and tomatoes.
It is important to note that beta-blockers can interfere with potassium transport into cells and potentially cause hyperkalaemia in renal failure patients. In contrast, beta-agonists such as Salbutamol are sometimes used as emergency treatment. Additionally, both unfractionated and low-molecular weight heparin can cause hyperkalaemia by inhibiting aldosterone secretion.
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This question is part of the following fields:
- Renal System
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Question 46
Incorrect
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A newborn with clubbed feet passes away shortly after birth due to severe respiratory distress. The mother did not receive any prenatal care. Autopsy reveals pulmonary hypoplasia.
What other clinical manifestations are likely to be present?Your Answer:
Correct Answer: Bilateral renal agenesis and oligohydramnios
Explanation:Potter sequence is a condition characterized by oligohydramnios, which can be caused by renal diseases like bilateral renal agenesis, ARPKD, and ADPKD. This condition often leads to pulmonary hypoplasia, clubbed feet, and cranial anomalies in neonates. However, oesophageal atresia, which causes polyhydramnios, is not associated with Potter sequence.
Understanding Autosomal Recessive Polycystic Kidney Disease (ARPKD)
Autosomal recessive polycystic kidney disease (ARPKD) is a rare genetic disorder that affects the kidneys and liver. Unlike the more common autosomal dominant polycystic kidney disease (ADPKD), ARPKD is caused by a defect in a gene on chromosome 6 that encodes fibrocystin, a protein essential for normal renal tubule development.
ARPKD is typically diagnosed during prenatal ultrasound or in early infancy when abdominal masses and renal failure are observed. Newborns with ARPKD may also exhibit features consistent with Potter’s syndrome due to oligohydramnios. The disease progresses rapidly, and end-stage renal failure usually develops in childhood. In addition to kidney involvement, patients with ARPKD often have liver complications such as portal and interlobular fibrosis.
Renal biopsy is a common diagnostic tool for ARPKD, which typically shows multiple cylindrical lesions at right angles to the cortical surface. Early diagnosis and management are crucial in improving outcomes for patients with ARPKD.
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This question is part of the following fields:
- Renal System
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Question 47
Incorrect
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Which one of the following changes are not typically seen in established dehydration?
Your Answer:
Correct Answer: Decreased serum urea to creatinine ratio
Explanation:The diagnosis of dehydration can be complex, with laboratory characteristics being a key factor to consider.
Pre-Operative Fluid Management Guidelines
Proper fluid management is crucial in preparing patients for surgery. The British Consensus guidelines on IV fluid therapy for Adult Surgical patients (GIFTASUP) and NICE (CG174 December 2013) have provided recommendations for pre-operative fluid management. These guidelines suggest the use of Ringer’s lactate or Hartmann’s for resuscitation or replacement of fluids, instead of 0.9% N. Saline due to the risk of hyperchloraemic acidosis. For maintenance fluids, 4%/0.18% dextrose saline or 5% dextrose should be used. Patients should not be nil by mouth for more than two hours, and carbohydrate-rich drinks should be given 2-3 hours before surgery. Mechanical bowel preparation should be avoided, but if used, simultaneous administration of Hartmann’s or Ringer’s lactate should be considered.
In cases of excessive fluid loss from vomiting, a crystalloid with potassium replacement should be given. Hartmann’s or Ringer lactate should be given for diarrhoea, ileostomy, ileus, obstruction, or sodium losses secondary to diuretics. High-risk patients should receive fluids and inotropes, and pre or operative hypovolaemia should be detected using flow-based measurements or clinical evaluation. In cases of blood loss or infection causing hypovolaemia, a balanced crystalloid or colloid should be used until blood is available. If IV fluid resuscitation is needed, crystalloids containing sodium in the range of 130-154 mmol/l should be used, with a bolus of 500 ml over less than 15 minutes. These guidelines aim to ensure that patients are properly hydrated and prepared for surgery, reducing the risk of complications and improving outcomes.
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This question is part of the following fields:
- Renal System
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Question 48
Incorrect
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A 27-year-old man is involved in a car crash resulting in a fracture of his right tibia. He undergoes fasciotomies and an external fixator is applied. Within 48 hours, his serum creatinine levels increase and his urine is analyzed, revealing the presence of muddy brown casts. What is the probable underlying diagnosis?
Your Answer:
Correct Answer: Acute tubular necrosis
Explanation:It is probable that the patient suffered from compartment syndrome due to a tibial fracture and subsequent fasciotomies, which can result in myoglobinuria. The combination of deteriorating kidney function and the presence of muddy brown casts in the urine strongly indicate acute tubular necrosis. Acute interstitial nephritis is typically caused by drug toxicity and does not typically lead to the presence of muddy brown casts in the urine.
Understanding the Difference between Acute Tubular Necrosis and Prerenal Uraemia
Acute kidney injury can be caused by various factors, including prerenal uraemia and acute tubular necrosis. It is important to differentiate between the two to determine the appropriate treatment. Prerenal uraemia occurs when the kidneys hold on to sodium to preserve volume, leading to decreased blood flow to the kidneys. On the other hand, acute tubular necrosis is caused by damage to the kidney tubules, which can be due to various factors such as toxins, infections, or ischemia.
To differentiate between the two, several factors can be considered. In prerenal uraemia, the urine sodium level is typically less than 20 mmol/L, while in acute tubular necrosis, it is usually greater than 40 mmol/L. The urine osmolality is also higher in prerenal uraemia, typically above 500 mOsm/kg, while in acute tubular necrosis, it is usually below 350 mOsm/kg. The fractional sodium excretion is less than 1% in prerenal uraemia, while it is greater than 1% in acute tubular necrosis. Additionally, the response to fluid challenge is typically good in prerenal uraemia, while it is poor in acute tubular necrosis.
Other factors that can help differentiate between the two include the serum urea:creatinine ratio, fractional urea excretion, urine:plasma osmolality, urine:plasma urea, specific gravity, and urine sediment. By considering these factors, healthcare professionals can accurately diagnose and treat acute kidney injury.
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This question is part of the following fields:
- Renal System
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Question 49
Incorrect
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Which one of the following statements relating to the regulation of cardiac blood flow is not true?
Your Answer:
Correct Answer: Systolic blood pressures of less than 65mmHg will cause the mesangial cells to secrete aldosterone
Explanation:The kidney has the ability to regulate its own blood supply within a certain range of systolic blood pressures. If the arterial pressure drops, the juxtaglomerular cells detect this and release renin, which activates the renin-angiotensin system. Mesangial cells, which are located in the tubule, do not have any direct endocrine function but are able to contract.
The Loop of Henle and its Role in Renal Physiology
The Loop of Henle is a crucial component of the renal system, located in the juxtamedullary nephrons and running deep into the medulla. Approximately 60 litres of water containing 9000 mmol sodium enters the descending limb of the loop of Henle in 24 hours. The osmolarity of fluid changes and is greatest at the tip of the papilla. The thin ascending limb is impermeable to water, but highly permeable to sodium and chloride ions. This loss means that at the beginning of the thick ascending limb the fluid is hypo osmotic compared with adjacent interstitial fluid. In the thick ascending limb, the reabsorption of sodium and chloride ions occurs by both facilitated and passive diffusion pathways. The loops of Henle are co-located with vasa recta, which have similar solute compositions to the surrounding extracellular fluid, preventing the diffusion and subsequent removal of this hypertonic fluid. The energy-dependent reabsorption of sodium and chloride in the thick ascending limb helps to maintain this osmotic gradient. Overall, the Loop of Henle plays a crucial role in regulating the concentration of solutes in the renal system.
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This question is part of the following fields:
- Renal System
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Question 50
Incorrect
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A 60-year-old patient visits the renal clinic after being diagnosed with stage 4 chronic kidney disease due to hypertension and diabetes. She inquires about the recommended diet for her condition.
What dietary advice should be provided to the patient?Your Answer:
Correct Answer: Low protein, phosphate, potassium and sodium
Explanation:For individuals with chronic kidney disease, it is recommended to follow a diet that is low in protein, phosphate, potassium, and sodium. This is because protein can produce ammonia, which is not effectively excreted by the kidneys in CKD. Phosphate can combine with calcium to form kidney stones, while sodium can raise blood pressure and further damage the kidneys. Potassium is also not efficiently eliminated by failing kidneys and can lead to irregular heartbeats.
Dietary Recommendations for Chronic Kidney Disease Patients
Chronic kidney disease patients are recommended to follow a specific diet that is low in protein, phosphate, sodium, and potassium. This dietary advice is given to reduce the strain on the kidneys, as these substances are typically excreted by the kidneys. By limiting the intake of these nutrients, patients can help slow the progression of their kidney disease and manage their symptoms more effectively. It is important for patients to work closely with their healthcare provider or a registered dietitian to ensure they are meeting their nutritional needs while following these dietary restrictions. With proper guidance and adherence to this diet, patients with chronic kidney disease can improve their overall health and quality of life.
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This question is part of the following fields:
- Renal System
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Question 51
Incorrect
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A 44-year-old woman presents to the emergency department with abdominal pain. She reports feeling generally unwell for the last 2 days but says today is the worst she has felt.
On examination, her heart rate is 110 beats/min with a blood pressure of 106/70mmHg and a respiratory rate of 27 breaths/min.
An arterial blood gas is taken:
pH 7.11 (7.35 - 7.45)
pO2 11.2 kPa (10.5 - 13.5)
pCO2 4.9 kPa (4.7 - 6.0)
Sodium 142 mmol/L (135 - 145)
Potassium 5.1 mmol/L (3.5 - 5.5)
Chloride 111 mmol/L (96 - 106)
Bicarbonate 17 mmol/L (22 - 28)
Lactate 2.6 mmol/L (0.6 - 1.9)
Glucose 10.5 mmol/L (4 - 7)
What is the most likely cause for this patient's investigation findings?Your Answer:
Correct Answer: Diarrhoea
Explanation:The patient’s condition is caused by diarrhoea, which is a common cause of normal anion gap metabolic acidosis. The anion gap is calculated by subtracting the sum of chloride and bicarbonate levels from the sum of sodium and potassium levels. In this case, the anion gap is within the normal range of 10-18 mmol/L. Other causes of normal anion gap metabolic acidosis include ureterosigmoidostomy, renal tubular acidosis, Addison’s disease, and certain medications. Raised anion gap metabolic acidosis can be remembered using the mnemonic ‘MUDPILES’, which includes causes such as methanol poisoning, diabetic ketoacidosis, and salicylate poisoning. However, these are not relevant in this case as the patient has a normal anion gap metabolic acidosis caused by diarrhoea.
Understanding Metabolic Acidosis
Metabolic acidosis is a condition that can be classified based on the anion gap, which is calculated by subtracting the sum of chloride and bicarbonate from the sum of sodium and potassium. The normal range for anion gap is 10-18 mmol/L. If a question provides the chloride level, it may be an indication to calculate the anion gap.
Hyperchloraemic metabolic acidosis is a type of metabolic acidosis with a normal anion gap. It can be caused by gastrointestinal bicarbonate loss, prolonged diarrhea, ureterosigmoidostomy, fistula, renal tubular acidosis, drugs like acetazolamide, ammonium chloride injection, and Addison’s disease. On the other hand, raised anion gap metabolic acidosis is caused by lactate, ketones, urate, acid poisoning, and other factors.
Lactic acidosis is a type of metabolic acidosis that is caused by high lactate levels. It can be further classified into two types: lactic acidosis type A, which is caused by sepsis, shock, hypoxia, and burns, and lactic acidosis type B, which is caused by metformin. Understanding the different types and causes of metabolic acidosis is important in diagnosing and treating the condition.
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This question is part of the following fields:
- Renal System
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Question 52
Incorrect
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A 6-year-old girl presents to the emergency department with her parents, who are concerned about her extremely swollen legs. The patient reports feeling fine and has no significant medical history.
Upon examination, there is pitting edema that extends to the lower abdominal wall. Laboratory tests confirm hypoalbuminemia.
A urine dipstick reveals ++++ proteinuria and no red blood cells.
What is the probable result of electron microscopy of a renal biopsy?Your Answer:
Correct Answer: Effacement of podocyte foot processes
Explanation:Effacement of podocyte foot processes is observed in minimal change disease on electron microscopy, indicating fusion of podocytes. This condition is the most common cause of nephrotic syndrome in children, which is characterized by hypoalbuminemia, edema, and marked proteinuria. Although normal glomerular architecture may be observed in minimal change disease when viewed with a light microscope, electron microscopy is necessary to detect the effacement of podocyte foot processes. Kimmelstiel-Wilson lesions are not a feature of minimal change disease, as they are commonly observed in diabetic nephropathy. Similarly, mesangial cell proliferation is not a hallmark of minimal change disease, as it is typically observed in membranoproliferative glomerulonephritis, which presents as a nephritic syndrome and is not consistent with the patient’s symptoms. Overall, minimal change disease is typically responsive to steroid treatment and has a favorable prognosis.
Minimal change disease is a condition that typically presents as nephrotic syndrome, with children accounting for 75% of cases and adults accounting for 25%. While most cases are idiopathic, a cause can be found in around 10-20% of cases, such as drugs like NSAIDs and rifampicin, Hodgkin’s lymphoma, thymoma, or infectious mononucleosis. The pathophysiology of the disease involves T-cell and cytokine-mediated damage to the glomerular basement membrane, resulting in polyanion loss and a reduction of electrostatic charge, which increases glomerular permeability to serum albumin.
The features of minimal change disease include nephrotic syndrome, normotension (hypertension is rare), and highly selective proteinuria, where only intermediate-sized proteins like albumin and transferrin leak through the glomerulus. Renal biopsy shows normal glomeruli on light microscopy, while electron microscopy shows fusion of podocytes and effacement of foot processes.
Management of minimal change disease involves oral corticosteroids, which are effective in 80% of cases. For steroid-resistant cases, cyclophosphamide is the next step. The prognosis for the disease is generally good, although relapse is common. Roughly one-third of patients have just one episode, one-third have infrequent relapses, and one-third have frequent relapses that stop before adulthood.
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This question is part of the following fields:
- Renal System
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Question 53
Incorrect
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A 58-year-old man is having a radical nephrectomy performed through a posterior approach. What is the structure that is most likely to be encountered during the surgical procedure?
Your Answer:
Correct Answer: 12th rib
Explanation:During a posterior approach, the kidneys may come across the 11th and 12th ribs which are located at the back. It is important to note that a potential complication of this surgery is the occurrence of a pneumothorax.
Renal Anatomy: Understanding the Structure and Relations of the Kidneys
The kidneys are two bean-shaped organs located in a deep gutter alongside the vertebral bodies. They measure about 11cm long, 5cm wide, and 3 cm thick, with the left kidney usually positioned slightly higher than the right. The upper pole of both kidneys approximates with the 11th rib, while the lower border is usually alongside L3. The kidneys are surrounded by an outer cortex and an inner medulla, which contains pyramidal structures that terminate at the renal pelvis into the ureter. The renal sinus lies within the kidney and contains branches of the renal artery, tributaries of the renal vein, major and minor calyces, and fat.
The anatomical relations of the kidneys vary depending on the side. The right kidney is in direct contact with the quadratus lumborum, diaphragm, psoas major, and transversus abdominis, while the left kidney is in direct contact with the quadratus lumborum, diaphragm, psoas major, transversus abdominis, stomach, pancreas, spleen, and distal part of the small intestine. Each kidney and suprarenal gland is enclosed within a common layer of investing fascia, derived from the transversalis fascia, which is divided into anterior and posterior layers (Gerotas fascia).
At the renal hilum, the renal vein lies most anteriorly, followed by the renal artery (an end artery), and the ureter lies most posteriorly. Understanding the structure and relations of the kidneys is crucial in diagnosing and treating renal diseases and disorders.
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This question is part of the following fields:
- Renal System
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Question 54
Incorrect
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A 70-year-old man visits the endocrinology clinic complaining of muscle cramps, headaches, and lethargy. During the clinic visit, his vital signs are heart rate 80/min, respiratory rate 18/min, blood pressure 150/100 mmHg, temperature 36.5ºC, and saturations 99% on air. Recent blood tests reveal:
- Na+ 147 mmol/L (135 - 145)
- K+ 3.2 mmol/L (3.5 - 5.0)
- Bicarbonate 28 mmol/L (22 - 29)
- Urea 6.0 mmol/L (2.0 - 7.0)
- Creatinine 95 µmol/L (55 - 120)
An adrenal mass is detected on his abdominal CT scan. Can you identify where the hormone responsible for his symptoms is produced?Your Answer:
Correct Answer: Zona glomerulosa
Explanation:The correct answer is the zona glomerulosa. This patient is experiencing symptoms of hyperaldosteronism, which is likely caused by an adenoma in the zona glomerulosa, as indicated by the mass seen on CT scan (also known as Conn’s syndrome). The adenoma stimulates the production of aldosterone, leading to hypertension and hypokalemia.
The adrenal medulla produces catecholamines, such as adrenaline and noradrenaline.
The juxtaglomerular apparatus is located in the kidney and produces renin in response to decreased renal perfusion.
The zona fasciculata is the middle layer of the adrenal cortex and is responsible for producing glucocorticoids, such as cortisol.
The zona reticularis is the innermost layer of the adrenal cortex and produces androgens, such as dehydroepiandrosterone (DHEA).
The renin-angiotensin-aldosterone system is a complex system that regulates blood pressure and fluid balance in the body. The adrenal cortex is divided into three zones, each producing different hormones. The zona glomerulosa produces mineralocorticoids, mainly aldosterone, which helps regulate sodium and potassium levels in the body. Renin is an enzyme released by the renal juxtaglomerular cells in response to reduced renal perfusion, hyponatremia, and sympathetic nerve stimulation. It hydrolyses angiotensinogen to form angiotensin I, which is then converted to angiotensin II by angiotensin-converting enzyme in the lungs. Angiotensin II has various actions, including causing vasoconstriction, stimulating thirst, and increasing proximal tubule Na+/H+ activity. It also stimulates aldosterone and ADH release, which causes retention of Na+ in exchange for K+/H+ in the distal tubule.
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This question is part of the following fields:
- Renal System
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Question 55
Incorrect
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Which serum protein is most likely to increase in a patient with severe sepsis?
Your Answer:
Correct Answer: Ferritin
Explanation:During an acute phase response, ferritin levels can significantly rise while other parameters typically decrease.
Acute Phase Proteins and their Role in the Body’s Response to Infection
During an infection or injury, the body undergoes an acute phase response where it produces a variety of proteins to help fight off the infection and promote healing. These proteins are known as acute phase proteins and include CRP, procalcitonin, ferritin, fibrinogen, alpha-1 antitrypsin, ceruloplasmin, serum amyloid A, serum amyloid P component, haptoglobin, and complement.
CRP is a commonly measured acute phase protein that is synthesized in the liver and binds to bacterial cells and those undergoing apoptosis. It is able to activate the complement system and its levels are known to rise in patients following surgery. Procalcitonin is another acute phase protein that is used as a marker for bacterial infections. Ferritin is involved in iron storage and transport, while fibrinogen is important for blood clotting. Alpha-1 antitrypsin helps protect the lungs from damage, and ceruloplasmin is involved in copper transport. Serum amyloid A and serum amyloid P component are involved in inflammation, while haptoglobin binds to hemoglobin to prevent its breakdown. Complement is a group of proteins that help to destroy pathogens.
During the acute phase response, the liver decreases the production of other proteins known as negative acute phase proteins, including albumin, transthyretin, transferrin, retinol binding protein, and cortisol binding protein. These proteins are important for maintaining normal bodily functions, but their production is decreased during an infection or injury to allow for the production of acute phase proteins.
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This question is part of the following fields:
- Renal System
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Question 56
Incorrect
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A 26-year-old man falls and lands on a manhole cover, resulting in an injury to his anterior bulbar urethra. Where is the likely location for the accumulation of extravasated urine?
Your Answer:
Correct Answer: Connective tissue of the scrotum
Explanation:The section of the urethra located between the perineal membrane and the membranous layer of the superficial fascia is tightly bound to the ischiopubic rami. This prevents urine from leaking backwards as the two layers are seamlessly connected around the superficial transverse perineal muscles.
Lower Genitourinary Tract Trauma: Types of Injury and Management
Lower genitourinary tract trauma can occur due to blunt trauma, with most bladder injuries associated with pelvic fractures. However, these injuries can easily be overlooked during trauma assessment. Up to 10% of male pelvic fractures are associated with urethral or bladder injuries.
Urethral injuries mainly occur in males and can be identified by blood at the meatus in 50% of cases. There are two types of urethral injury: bulbar rupture, which is the most common and often caused by straddle-type injuries such as bicycles, and membranous rupture, which can be extra or intraperitoneal and commonly caused by pelvic fractures. Penile or perineal oedema/hematoma and displacement of the prostate upwards during PR examination are also signs of urethral injury. An ascending urethrogram is used for investigation, and management involves surgical placement of a suprapubic catheter.
External genitalia injuries, such as those to the penis and scrotum, can be caused by penetration, blunt trauma, continence- or sexual pleasure-enhancing devices, and mutilation.
Bladder injuries can be intra or extraperitoneal and present with haematuria or suprapubic pain. A history of pelvic fracture and inability to void should always raise suspicion of bladder or urethral injury. Inability to retrieve all fluid used to irrigate the bladder through a Foley catheter also indicates bladder injury. IVU or cystogram is used for investigation, and management involves laparotomy if intraperitoneal and conservative treatment if extraperitoneal.
In summary, lower genitourinary tract trauma can result in urethral or bladder injuries, which can be identified through various signs and symptoms. Proper investigation and management are crucial for successful treatment.
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This question is part of the following fields:
- Renal System
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Question 57
Incorrect
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A middle-aged woman presents with collapse and weakness on her left side. Her husband reports that she has a medical history of hyperthyroidism, diabetes, and autosomal dominant polycystic kidney disease, but no known drug allergies. A CT scan of her head reveals a significant intracerebral bleed on the left side. What is the probable cause of the bleed?
Your Answer:
Correct Answer: Ruptured berry aneurysm
Explanation:Autosomal dominant polycystic kidney disease increases the risk of brain haemorrhage due to ruptured berry aneurysms.
Autosomal dominant polycystic kidney disease (ADPKD) is a commonly inherited kidney disease that affects 1 in 1,000 Caucasians. The disease is caused by mutations in two genes, PKD1 and PKD2, which produce polycystin-1 and polycystin-2 respectively. ADPKD type 1 accounts for 85% of cases, while ADPKD type 2 accounts for 15% of cases. ADPKD type 1 is caused by a mutation in the PKD1 gene on chromosome 16, while ADPKD type 2 is caused by a mutation in the PKD2 gene on chromosome 4. ADPKD type 1 tends to present with renal failure earlier than ADPKD type 2.
To screen for ADPKD in relatives of affected individuals, an abdominal ultrasound is recommended. The diagnostic criteria for ultrasound include the presence of two cysts, either unilateral or bilateral, if the individual is under 30 years old. If the individual is between 30-59 years old, two cysts in both kidneys are required for diagnosis. If the individual is over 60 years old, four cysts in both kidneys are necessary for diagnosis.
For some patients with ADPKD, tolvaptan, a vasopressin receptor 2 antagonist, may be an option to slow the progression of cyst development and renal insufficiency. However, NICE recommends tolvaptan only for adults with ADPKD who have chronic kidney disease stage 2 or 3 at the start of treatment, evidence of rapidly progressing disease, and if the company provides it with the agreed discount in the patient access scheme.
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This question is part of the following fields:
- Renal System
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Question 58
Incorrect
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A 25-year-old patient arrives at the emergency department with a head injury after a night of heavy drinking. All his vital signs are normal, and his pupils react to light equally. A CT scan of his head shows no abnormalities. He reports feeling thirsty and experiencing excessive urination.
What is causing his polyuria?Your Answer:
Correct Answer: Inhibition of posterior pituitary gland
Explanation:Excessive alcohol consumption can result in the suppression of ADH in the posterior pituitary gland, which can lead to polyuria.
Normally, dehydration causes an increase in plasma osmolality, which triggers the release of vasopressin (antidiuretic hormone) from the posterior pituitary gland. This hormone increases the insertion of aquaporin 2 channels in the distal convoluted tubules and collecting duct in the kidney, which in turn increases water reabsorption. This leads to a decrease in plasma osmolality and a reduction in the volume of urine produced, i.e., antidiuretic.
However, alcohol inhibits this mechanism, resulting in polyuria and dehydration. Polyuria can then cause thirst, i.e., polydipsia.
It is important to note that the sugars in alcohol do not typically cause osmotic diuresis unless there is an underlying condition such as diabetes and hyperglycemia.
Polyuria, or excessive urination, can be caused by a variety of factors. A recent review in the BMJ categorizes these causes by their frequency of occurrence. The most common causes of polyuria include the use of diuretics, caffeine, and alcohol, as well as diabetes mellitus, lithium, and heart failure. Less common causes include hypercalcaemia and hyperthyroidism, while rare causes include chronic renal failure, primary polydipsia, and hypokalaemia. The least common cause of polyuria is diabetes insipidus, which occurs in less than 1 in 10,000 cases. It is important to note that while these frequencies may not align with exam questions, understanding the potential causes of polyuria can aid in diagnosis and treatment.
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This question is part of the following fields:
- Renal System
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Question 59
Incorrect
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Samantha is a 58-year-old woman who has been experiencing symptoms of urinary urgency and frequency. She is curious about the accuracy of the PSA test and would like to know what percentage of patients with an elevated PSA level (for their age) do not actually have prostate cancer.
Approximately what percentage of patients with a raised PSA level (relative to their age) do not have prostate cancer?Your Answer:
Correct Answer: 75%
Explanation:PSA Testing for Prostate Cancer
Prostate specific antigen (PSA) is an enzyme produced by the prostate gland, and it is used as a tumour marker for prostate cancer. However, there is still much debate about its usefulness as a screening tool. The NHS Prostate Cancer Risk Management Programme (PCRMP) has published guidelines on how to handle requests for PSA testing in asymptomatic men. The National Screening Committee has decided not to introduce a prostate cancer screening programme yet, but rather allow men to make an informed choice.
The PCRMP has recommended age-adjusted upper limits for PSA, while NICE Clinical Knowledge Summaries suggest a lower threshold for referral. However, PSA levels may also be raised by other conditions such as benign prostatic hyperplasia, prostatitis, urinary tract infection, ejaculation, vigorous exercise, urinary retention, and instrumentation of the urinary tract.
PSA testing has poor specificity and sensitivity, and various methods are used to try and add greater meaning to a PSA level, including age-adjusted upper limits and monitoring change in PSA level with time. It is important to note that digital rectal examination may or may not cause a rise in PSA levels, which is a matter of debate.
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This question is part of the following fields:
- Renal System
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Question 60
Incorrect
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A 25-year-old suffers a groin stab wound resulting in hypovolaemic shock. What would be the probable observation on examining his urine?
Your Answer:
Correct Answer: Increased specific gravity
Explanation:When blood pressure drops below the level at which the kidney can regulate its blood flow, hypovolemic shock can lead to a reduction in renal blood flow. This can cause an increase in specific gravity as the body tries to retain water to maintain blood volume.
The Loop of Henle and its Role in Renal Physiology
The Loop of Henle is a crucial component of the renal system, located in the juxtamedullary nephrons and running deep into the medulla. Approximately 60 litres of water containing 9000 mmol sodium enters the descending limb of the loop of Henle in 24 hours. The osmolarity of fluid changes and is greatest at the tip of the papilla. The thin ascending limb is impermeable to water, but highly permeable to sodium and chloride ions. This loss means that at the beginning of the thick ascending limb the fluid is hypo osmotic compared with adjacent interstitial fluid. In the thick ascending limb, the reabsorption of sodium and chloride ions occurs by both facilitated and passive diffusion pathways. The loops of Henle are co-located with vasa recta, which have similar solute compositions to the surrounding extracellular fluid, preventing the diffusion and subsequent removal of this hypertonic fluid. The energy-dependent reabsorption of sodium and chloride in the thick ascending limb helps to maintain this osmotic gradient. Overall, the Loop of Henle plays a crucial role in regulating the concentration of solutes in the renal system.
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This question is part of the following fields:
- Renal System
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Question 61
Incorrect
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A 95-year-old man is discovered collapsed in his residence and is transported to the hospital. Upon examination, he is diagnosed with dehydration and hypotension, prompting the release of renin by the juxtaglomerular cells. What is the mechanism of action of renin?
Your Answer:
Correct Answer: Hydrolyse angiotensinogen to form angiotensin I
Explanation:Angiotensin I is formed when renin breaks down angiotensinogen, which is a process that occurs within the renin-angiotensin-aldosterone system and is facilitated by juxtaglomerular cells.
The renin-angiotensin-aldosterone system is a complex system that regulates blood pressure and fluid balance in the body. The adrenal cortex is divided into three zones, each producing different hormones. The zona glomerulosa produces mineralocorticoids, mainly aldosterone, which helps regulate sodium and potassium levels in the body. Renin is an enzyme released by the renal juxtaglomerular cells in response to reduced renal perfusion, hyponatremia, and sympathetic nerve stimulation. It hydrolyses angiotensinogen to form angiotensin I, which is then converted to angiotensin II by angiotensin-converting enzyme in the lungs. Angiotensin II has various actions, including causing vasoconstriction, stimulating thirst, and increasing proximal tubule Na+/H+ activity. It also stimulates aldosterone and ADH release, which causes retention of Na+ in exchange for K+/H+ in the distal tubule.
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This question is part of the following fields:
- Renal System
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Question 62
Incorrect
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A 56-year-old presents to his general physician with painless haematuria and is urgently referred to urology due to a certain risk factor in his history. The urologist performs a flexible cystoscopy and discovers bladder cancer, which is later confirmed by a bladder biopsy. What could have prompted the general physician to make an urgent referral?
Your Answer:
Correct Answer: Exposure to 2-Naphthylamine
Explanation:The primary intravesical immunotherapy for early-stage bladder cancer is Bacillus Calmette-Guerin (BCG), which does not pose a risk for bladder cancer. There is no evidence to suggest that aspirin has any impact on the risk of bladder cancer. However, exposure to hydrocarbons like 2-Naphthylamine is a known risk factor for bladder cancer.
Bladder cancer is a common urological cancer that primarily affects males aged 50-80 years old. Smoking and exposure to hydrocarbons increase the risk of developing the disease. Chronic bladder inflammation from Schistosomiasis infection is also a common cause of squamous cell carcinomas in countries where the disease is endemic. Benign tumors of the bladder, such as inverted urothelial papilloma and nephrogenic adenoma, are rare. The most common bladder malignancies are urothelial (transitional cell) carcinoma, squamous cell carcinoma, and adenocarcinoma. Urothelial carcinomas may be solitary or multifocal, with papillary growth patterns having a better prognosis. The remaining tumors may be of higher grade and prone to local invasion, resulting in a worse prognosis.
The TNM staging system is used to describe the extent of bladder cancer. Most patients present with painless, macroscopic hematuria, and a cystoscopy and biopsies or TURBT are used to provide a histological diagnosis and information on depth of invasion. Pelvic MRI and CT scanning are used to determine locoregional spread, and PET CT may be used to investigate nodes of uncertain significance. Treatment options include TURBT, intravesical chemotherapy, surgery (radical cystectomy and ileal conduit), and radical radiotherapy. The prognosis varies depending on the stage of the cancer, with T1 having a 90% survival rate and any T, N1-N2 having a 30% survival rate.
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This question is part of the following fields:
- Renal System
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Question 63
Incorrect
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A 79-year-old woman is admitted with confusion and started on an IV infusion after blood tests are taken. Her admission blood results indicate dehydration and elevated potassium levels, with a subsequent increase to 5.9. Which intravenous therapy is likely causing her hyperkalaemia?
Your Answer:
Correct Answer: Hartmann’s
Explanation:Fluid Therapy Guidelines for Junior Doctors
Fluid therapy is a common task for junior doctors, and it is important to follow guidelines to ensure patients receive the appropriate amount of fluids. The 2013 NICE guidelines recommend 25-30 ml/kg/day of water, 1 mmol/kg/day of potassium, sodium, and chloride, and 50-100 g/day of glucose for maintenance fluids. For the first 24 hours, NICE recommends using sodium chloride 0.18% in 4% glucose with 27 mmol/l potassium. However, the amount of fluid required may vary depending on the patient’s medical history. For example, a post-op patient with significant fluid loss will require more fluid, while a patient with heart failure should receive less fluid to avoid pulmonary edema.
It is important to consider the electrolyte concentrations of plasma and the most commonly used fluids when prescribing intravenous fluids. 0.9% saline can lead to hyperchloraemic metabolic acidosis if large volumes are used. Hartmann’s solution contains potassium and should not be used in patients with hyperkalemia. By following these guidelines and considering individual patient needs, junior doctors can ensure safe and effective fluid therapy.
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This question is part of the following fields:
- Renal System
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Question 64
Incorrect
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A 40-year-old man visits his doctor for a routine check-up and is informed that his cholesterol levels are elevated. He has a significant family history of high cholesterol and genetic testing reveals that he is heterozygous for the affected allele. If he has a child with a woman who does not carry the affected allele, what is the probability that their child will inherit the condition?
Your Answer:
Correct Answer: 50%
Explanation:Familial Hypercholesterolaemia: Causes, Diagnosis, and Management
Familial hypercholesterolaemia (FH) is a genetic condition that affects approximately 1 in 500 people. It is an autosomal dominant disorder that results in high levels of LDL-cholesterol, which can lead to early cardiovascular disease if left untreated. FH is caused by mutations in the gene that encodes the LDL-receptor protein.
To diagnose FH, NICE recommends suspecting it as a possible diagnosis in adults with a total cholesterol level greater than 7.5 mmol/l and/or a personal or family history of premature coronary heart disease. For children of affected parents, testing should be arranged by age 10 if one parent is affected and by age 5 if both parents are affected.
The Simon Broome criteria are used for clinical diagnosis, which includes a total cholesterol level greater than 7.5 mmol/l and LDL-C greater than 4.9 mmol/l in adults or a total cholesterol level greater than 6.7 mmol/l and LDL-C greater than 4.0 mmol/l in children. Definite FH is diagnosed if there is tendon xanthoma in patients or first or second-degree relatives or DNA-based evidence of FH. Possible FH is diagnosed if there is a family history of myocardial infarction below age 50 years in second-degree relatives, below age 60 in first-degree relatives, or a family history of raised cholesterol levels.
Management of FH involves referral to a specialist lipid clinic and the use of high-dose statins as first-line treatment. CVD risk estimation using standard tables is not appropriate in FH as they do not accurately reflect the risk of CVD. First-degree relatives have a 50% chance of having the disorder and should be offered screening, including children who should be screened by the age of 10 years if there is one affected parent. Statins should be discontinued in women 3 months before conception due to the risk of congenital defects.
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This question is part of the following fields:
- Renal System
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Question 65
Incorrect
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An 73-year-old man visits his doctor complaining of limb weakness, fatigue, and easy bruising. Despite maintaining a healthy diet, he has noticed an increase in abdominal weight. Following a positive high dexamethasone test, he is diagnosed with Cushing's disease caused by a pituitary adenoma. Which part of the adrenal gland produces the hormone responsible for his symptoms' pathophysiology?
Your Answer:
Correct Answer: Zona fasciculata
Explanation:The correct answer is the zona fasciculata of the adrenal cortex.
This patient’s symptoms suggest that they may have Cushing’s syndrome, which is caused by excess cortisol production. Cortisol is normally produced in the zona fasciculata of the adrenal cortex.
The adrenal medulla produces catecholamines like adrenaline and noradrenaline.
The juxtaglomerular apparatus is located in the kidney and produces renin in response to reduced renal perfusion.
The zona glomerulosa is the outer layer of the adrenal cortex and produces mineralocorticoids like aldosterone.
The zona reticularis is the innermost layer of the adrenal cortex and produces androgens like DHEA.
The renin-angiotensin-aldosterone system is a complex system that regulates blood pressure and fluid balance in the body. The adrenal cortex is divided into three zones, each producing different hormones. The zona glomerulosa produces mineralocorticoids, mainly aldosterone, which helps regulate sodium and potassium levels in the body. Renin is an enzyme released by the renal juxtaglomerular cells in response to reduced renal perfusion, hyponatremia, and sympathetic nerve stimulation. It hydrolyses angiotensinogen to form angiotensin I, which is then converted to angiotensin II by angiotensin-converting enzyme in the lungs. Angiotensin II has various actions, including causing vasoconstriction, stimulating thirst, and increasing proximal tubule Na+/H+ activity. It also stimulates aldosterone and ADH release, which causes retention of Na+ in exchange for K+/H+ in the distal tubule.
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This question is part of the following fields:
- Renal System
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Question 66
Incorrect
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A 58-year-old man visits his primary care physician with complaints of painful urination and difficulty in emptying his bladder. He has a history of urinary tract infection and atrial fibrillation. During the examination, the physician notes an enlarged and tender prostate. The patient's vital signs are as follows: blood pressure 125/85 mmHg, pulse rate 96 beats per minute, temperature 38.9 ºC, and respiratory rate 24 breaths per minute. Which of the following organisms is most likely responsible for his symptoms?
Your Answer:
Correct Answer: E.coli
Explanation:The predominant cause of acute bacterial prostatitis (ABP) is E.coli, according to available data. Pneumocystis jirovecii is an opportunistic pathogen that typically causes pneumonia in immunocompromised individuals, particularly those with HIV and a CD count below 200. Treatment for this infection involves co-trimoxazole. There is no evidence of ABP being caused by tuberculosis mycobacterium in the literature.
Understanding Acute Bacterial Prostatitis
Acute bacterial prostatitis is a condition that occurs when gram-negative bacteria enter the prostate gland through the urethra. The most common pathogen that causes this condition is Escherichia coli. Risk factors for acute bacterial prostatitis include recent urinary tract infection, urogenital instrumentation, intermittent bladder catheterisation, and recent prostate biopsy.
Symptoms of acute bacterial prostatitis include pain in various areas such as the perineum, penis, rectum, or back. Obstructive voiding symptoms may also be present, along with fever and rigors. During a digital rectal examination, the prostate gland may feel tender and boggy.
To manage acute bacterial prostatitis, a 14-day course of a quinolone is currently recommended by Clinical Knowledge Summaries. It is also important to consider screening for sexually transmitted infections. Understanding the symptoms and risk factors of acute bacterial prostatitis can help individuals seek prompt medical attention and receive appropriate treatment.
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This question is part of the following fields:
- Renal System
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Question 67
Incorrect
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A woman presents with symptoms of agalactorrhoea, amenorrhoea, intolerance to cold, constipation, and weight loss six months after giving birth. She experienced postpartum bleeding during delivery and has now been diagnosed with hypopituitarism. What could be the possible reason for this condition?
Your Answer:
Correct Answer: Sheehan's syndrome
Explanation:Sheehan’s syndrome is a condition that arises from pituitary ischaemia, which is caused by blood loss during or after childbirth. The syndrome is characterized by symptoms that indicate global hypopituitarism, including agalactorrhoea (lack of prolactin), amenorrhoea (lack of FSH and LH), cold intolerance and constipation (lack of thyroid hormones), and weight loss (lack of steroid hormones).
Malignancy is an uncommon cause of hypopituitarism.
While pituitary adenoma is a frequent cause of hypopituitarism, it is unlikely to be the cause of this patient’s symptoms, given that they occurred after childbirth. Pituitary adenoma may also present with symptoms related to mass effect, such as headache and bilateral hemianopia.
Understanding Hypopituitarism: Causes, Symptoms, and Management
Hypopituitarism is a medical condition that occurs when the pituitary gland fails to produce enough hormones. This can be caused by various factors such as compression of the gland by non-secretory pituitary macroadenoma, pituitary apoplexy, Sheehan’s syndrome, hypothalamic tumors, trauma, iatrogenic irradiation, and infiltrative diseases like hemochromatosis and sarcoidosis. The symptoms of hypopituitarism depend on which hormones are deficient. For instance, low ACTH can cause tiredness and postural hypotension, while low FSH/LH can lead to amenorrhea, infertility, and loss of libido. Low TSH can cause constipation and feeling cold, while low GH can result in short stature if it occurs during childhood. Low prolactin can cause problems with lactation.
To diagnose hypopituitarism, hormone profile testing and imaging are usually conducted. Treatment involves addressing the underlying cause, such as surgical removal of pituitary macroadenoma, and replacement of deficient hormones. It is important to manage hypopituitarism promptly to prevent complications and improve the patient’s quality of life.
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This question is part of the following fields:
- Renal System
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Question 68
Incorrect
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A 42-year-old man visits the clinic complaining of a tickly cough that has been bothering him for the past two weeks. He reports no other symptoms and his respiratory exam appears normal. The patient recently began taking an ACE inhibitor, which you suspect may be the cause of his cough. You decide to switch him to an angiotensin receptor blocker instead. Many antihypertensive medications target components of the renin-angiotensin-aldosterone system. Which enzyme catalyzes the hydrolysis of angiotensinogen to produce the hormone angiotensin I, an important player in this system?
Your Answer:
Correct Answer: Renin
Explanation:The kidneys produce renin in their juxtaglomerular cells, which plays a crucial role in the renin-angiotensin-aldosterone system. This enzyme converts angiotensinogen into angiotensin I through a hydrolysis reaction. More information on this system can be found below.
Another important enzyme in this system is angiotensin-converting-enzyme (ACE), which is primarily located in the lungs but can also be found in smaller quantities in endothelial cells of the vasculature and kidney epithelial cells. ACE converts angiotensin I to angiotensin II and is the target of ACE inhibitors.
Carbonic anhydrase is an enzyme that facilitates the reaction between water and carbon dioxide to form bicarbonate, and it can also catalyze the reverse reaction. Carbonic anhydrase inhibitors target this enzyme.
Cyclooxygenase-2 (COX-2) is involved in the synthesis of prostaglandins, and NSAIDs are believed to work by inhibiting both COX-1 and COX-2 enzymes.
The renin-angiotensin-aldosterone system is a complex system that regulates blood pressure and fluid balance in the body. The adrenal cortex is divided into three zones, each producing different hormones. The zona glomerulosa produces mineralocorticoids, mainly aldosterone, which helps regulate sodium and potassium levels in the body. Renin is an enzyme released by the renal juxtaglomerular cells in response to reduced renal perfusion, hyponatremia, and sympathetic nerve stimulation. It hydrolyses angiotensinogen to form angiotensin I, which is then converted to angiotensin II by angiotensin-converting enzyme in the lungs. Angiotensin II has various actions, including causing vasoconstriction, stimulating thirst, and increasing proximal tubule Na+/H+ activity. It also stimulates aldosterone and ADH release, which causes retention of Na+ in exchange for K+/H+ in the distal tubule.
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This question is part of the following fields:
- Renal System
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Question 69
Incorrect
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A 75-year-old woman is admitted for a laparoscopic cholecystectomy. As part of her pre-operative evaluation, it is discovered that she is taking furosemide to manage her hypertension. What percentage of the sodium filtered at the glomerulus will be eliminated?
Your Answer:
Correct Answer: Up to 25%
Explanation:Loop diuretics cause significant increases in sodium excretion by acting on both the medullary and cortical regions of the thick ascending limb of the loop of Henle. This leads to a reduction in the medullary osmolal gradient and an increase in the excretion of free water, along with sodium loss. Unlike thiazide diuretics, which do not affect urine concentration and are more likely to cause hyponatremia, loop diuretics result in the loss of both sodium and water.
Diuretic drugs are classified into three major categories based on the location where they inhibit sodium reabsorption. Loop diuretics act on the thick ascending loop of Henle, thiazide diuretics on the distal tubule and connecting segment, and potassium sparing diuretics on the aldosterone-sensitive principal cells in the cortical collecting tubule. Sodium is reabsorbed in the kidney through Na+/K+ ATPase pumps located on the basolateral membrane, which return reabsorbed sodium to the circulation and maintain low intracellular sodium levels. This ensures a constant concentration gradient.
The physiological effects of commonly used diuretics vary based on their site of action. furosemide, a loop diuretic, inhibits the Na+/K+/2Cl- carrier in the ascending limb of the loop of Henle and can result in up to 25% of filtered sodium being excreted. Thiazide diuretics, which act on the distal tubule and connecting segment, inhibit the Na+Cl- carrier and typically result in between 3 and 5% of filtered sodium being excreted. Finally, spironolactone, a potassium sparing diuretic, inhibits the Na+/K+ ATPase pump in the cortical collecting tubule and typically results in between 1 and 2% of filtered sodium being excreted.
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This question is part of the following fields:
- Renal System
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Question 70
Incorrect
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A 3-year-old toddler is brought to the paediatric department due to stunted growth. During the medical history-taking, it is revealed that the parents are first cousins. Genetic testing confirms the diagnosis of Fanconi syndrome, which is known to cause renal dysfunction and electrolyte imbalances. The child's blood test results are as follows:
- Calcium: 2.4 mmol/L (normal range: 2.1-2.6)
- Phosphate: 0.3 mmol/L (normal range: 0.8-1.4)
- Magnesium: 0.9 mmol/L (normal range: 0.7-1.0)
Which part of the nephron is likely affected in this case, leading to the electrolyte disturbance observed in the patient?Your Answer:
Correct Answer: Proximal convoluted tubule
Explanation:The proximal convoluted tubule is where the majority of renal phosphate reabsorption occurs. This is relevant to a patient with hypophosphataemia, as dysfunction of the proximal convoluted tubule can lead to this condition. In addition to phosphate, the proximal convoluted tubule also reabsorbs glucose, amino acids, bicarbonate, sodium, and potassium.
The collecting duct, distal convoluted tubule, and glomerulus are not involved in the reabsorption of phosphate. The collecting duct regulates water reabsorption, the distal convoluted tubule plays a role in acid-base balance, and the glomerulus performs ultrafiltration. Thiazides and aldosterone antagonists act on the distal convoluted tubule.
The Loop of Henle and its Role in Renal Physiology
The Loop of Henle is a crucial component of the renal system, located in the juxtamedullary nephrons and running deep into the medulla. Approximately 60 litres of water containing 9000 mmol sodium enters the descending limb of the loop of Henle in 24 hours. The osmolarity of fluid changes and is greatest at the tip of the papilla. The thin ascending limb is impermeable to water, but highly permeable to sodium and chloride ions. This loss means that at the beginning of the thick ascending limb the fluid is hypo osmotic compared with adjacent interstitial fluid. In the thick ascending limb, the reabsorption of sodium and chloride ions occurs by both facilitated and passive diffusion pathways. The loops of Henle are co-located with vasa recta, which have similar solute compositions to the surrounding extracellular fluid, preventing the diffusion and subsequent removal of this hypertonic fluid. The energy-dependent reabsorption of sodium and chloride in the thick ascending limb helps to maintain this osmotic gradient. Overall, the Loop of Henle plays a crucial role in regulating the concentration of solutes in the renal system.
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This question is part of the following fields:
- Renal System
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Question 71
Incorrect
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A 25-year-old male presents to his GP with recurrent episodes of haematuria. He reports having a sore throat and mild cough for the past three days. Upon examination, his urine dipstick is negative for leukocytes and nitrates. His vital signs are as follows: SpO2 99%, respiratory rate 16/min, blood pressure 140/90mmHg, heart rate 80bpm, and temperature 37.1ºC. The initial blood results show a Hb of 14.8 g/dL, platelets of 290 * 109/L, WBC of 14.9 * 109/L, Na+ of 138 mmol/L, K+ of 4.5 mmol/L, urea of 7.2 mmol/L, creatinine of 150 µmol/L, and CRP of 1.2 mg/L. What is the most likely mechanism responsible for his haematuria?
Your Answer:
Correct Answer: Immune complex deposition
Explanation:The likely diagnosis for the man is IgA nephropathy, which is characterized by immune complex deposition in the glomerulus and recurrent macroscopic haematuria following an upper respiratory tract infection. Disseminated intravascular coagulation (DIC) caused by activation of the coagulation cascade and damage from toxins such as Shiga toxin in haemolytic uraemic syndrome are not responsible mechanisms for IgA nephropathy. Benign prostatic hypertrophy (BPH), which is caused by hypertrophy of prostatic cells, can also cause haematuria, but it is unlikely in this patient as it typically affects older men and presents with other urinary symptoms.
Understanding IgA Nephropathy
IgA nephropathy, also known as Berger’s disease, is the most common cause of glomerulonephritis worldwide. It typically presents as macroscopic haematuria in young people following an upper respiratory tract infection. The condition is thought to be caused by mesangial deposition of IgA immune complexes, and there is considerable pathological overlap with Henoch-Schonlein purpura (HSP). Histology shows mesangial hypercellularity and positive immunofluorescence for IgA and C3.
Differentiating between IgA nephropathy and post-streptococcal glomerulonephritis is important. Post-streptococcal glomerulonephritis is associated with low complement levels and the main symptom is proteinuria, although haematuria can occur. There is typically an interval between URTI and the onset of renal problems in post-streptococcal glomerulonephritis.
Management of IgA nephropathy depends on the severity of the condition. If there is isolated hematuria, no or minimal proteinuria, and a normal glomerular filtration rate (GFR), no treatment is needed other than follow-up to check renal function. If there is persistent proteinuria and a normal or only slightly reduced GFR, initial treatment is with ACE inhibitors. If there is active disease or failure to respond to ACE inhibitors, immunosuppression with corticosteroids may be necessary.
The prognosis for IgA nephropathy varies. 25% of patients develop ESRF. Markers of good prognosis include frank haematuria, while markers of poor prognosis include male gender, proteinuria (especially > 2 g/day), hypertension, smoking, hyperlipidaemia, and ACE genotype DD.
Overall, understanding IgA nephropathy is important for proper diagnosis and management of the condition. Proper management can help improve outcomes and prevent progression to ESRF.
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This question is part of the following fields:
- Renal System
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Question 72
Incorrect
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A 58-year-old man has had a radical nephrectomy. Upon bisecting the kidney, the pathologist observes a pink fleshy tumor in the renal pelvis. What is the probable illness?
Your Answer:
Correct Answer: Transitional cell carcinoma
Explanation:Renal tumours typically have a yellow or brown hue, but TCCs stand out as they have a pink appearance. If a TCC is detected in the renal pelvis, a nephroureterectomy is necessary.
Renal Lesions: Types, Features, and Treatments
Renal lesions refer to abnormal growths or masses that develop in the kidneys. There are different types of renal lesions, each with its own disease-specific features and treatment options. Renal cell carcinoma is the most common renal tumor, accounting for 85% of cases. It often presents with haematuria and may cause hypertension and polycythaemia as paraneoplastic features. Treatment usually involves radical or partial nephrectomy.
Nephroblastoma, also known as Wilms tumor, is a rare childhood tumor that accounts for 80% of all genitourinary malignancies in those under the age of 15 years. It often presents with a mass and hypertension. Diagnostic workup includes ultrasound and CT scanning, and treatment involves surgical resection combined with chemotherapy. Neuroblastoma is the most common extracranial tumor of childhood, with up to 80% occurring in those under 4 years of age. It is a tumor of neural crest origin and may be diagnosed using MIBG scanning. Treatment involves surgical resection, radiotherapy, and chemotherapy.
Transitional cell carcinoma accounts for 90% of lower urinary tract tumors but only 10% of renal tumors. It often presents with painless haematuria and may be caused by occupational exposure to industrial dyes and rubber chemicals. Diagnosis and staging are done with CT IVU, and treatment involves radical nephroureterectomy. Angiomyolipoma is a hamartoma type lesion that occurs sporadically in 80% of cases and in those with tuberous sclerosis in the remaining cases. It is composed of blood vessels, smooth muscle, and fat and may cause massive bleeding in 10% of cases. Surgical resection is required for lesions larger than 4 cm and causing symptoms.
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This question is part of the following fields:
- Renal System
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Question 73
Incorrect
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A 20-year-old male presents with lethargy and heavy proteinuria on urinalysis. The consultant wants to directly measure renal function. What test will you order?
Your Answer:
Correct Answer: Inulin clearance
Explanation:Inulin is an ideal substance for measuring creatinine clearance as it is completely filtered at the glomerulus and not secreted or reabsorbed by the tubules. This provides a direct measurement of CrCl, making it the gold standard.
However, the MDRD equation is commonly used to estimate eGFR by considering creatinine, age, sex, and ethnicity. It may not be accurate for individuals with varying muscle mass, such as a muscular young man who may produce more creatinine and have an underestimated CrCl.
The Cockcroft-Gault equation is considered superior to MDRD as it also takes into account the patient’s weight, age, sex, and creatinine levels.
Reabsorption and Secretion in Renal Function
In renal function, reabsorption and secretion play important roles in maintaining homeostasis. The filtered load is the amount of a substance that is filtered by the glomerulus and is determined by the glomerular filtration rate (GFR) and the plasma concentration of the substance. The excretion rate is the amount of the substance that is eliminated in the urine and is determined by the urine flow rate and the urine concentration of the substance. Reabsorption occurs when the filtered load is greater than the excretion rate, and secretion occurs when the excretion rate is greater than the filtered load.
The reabsorption rate is the difference between the filtered load and the excretion rate, and the secretion rate is the difference between the excretion rate and the filtered load. Reabsorption and secretion can occur in different parts of the nephron, including the proximal tubule, loop of Henle, distal tubule, and collecting duct. These processes are regulated by various hormones and signaling pathways, such as aldosterone, antidiuretic hormone (ADH), and atrial natriuretic peptide (ANP).
Overall, reabsorption and secretion are important mechanisms for regulating the composition of the urine and maintaining fluid and electrolyte balance in the body. Dysfunction of these processes can lead to various renal disorders, such as diabetes insipidus, renal tubular acidosis, and Fanconi syndrome.
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This question is part of the following fields:
- Renal System
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Question 74
Incorrect
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A 28-year-old male patient comes to you with worries about his increasing breast size, despite not experiencing any weight gain in other areas. Upon further inquiry, he also mentions a painless lump in his right testicle. He reveals that his father had testicular cancer in the past.
What is the probable reason for gynaecomastia in this scenario?Your Answer:
Correct Answer: Increased oestrogen: androgen ratio
Explanation:Gynaecomastia is a common symptom of testicular cancer and is caused by an increased oestrogen:androgen ratio. This occurs because germ-cell tumours produce hCG, which causes Leydig cells to produce more oestradiol in relation to testosterone. Leydig cell tumours also directly secrete more oestradiol and convert additional androgen precursors to oestrogens. This results in a relative reduction in androgen concentration and an increased conversion of androgens to oestrogens.
Obesity can also cause gynaecomastia due to increased levels of aromatase, the enzyme responsible for the conversion of androgens to oestrogens. However, this is not the most likely cause in this case as the patient has not gained weight elsewhere and presents with symptoms of testicular cancer.
Undescended testis is a significant risk factor for testicular cancer, but it is not a direct cause of gynaecomastia. Similarly, a prolactinoma can cause breast enlargement in males, but it is not commonly associated with testicular cancer or gynaecomastia.
In summary, gynaecomastia in testicular cancer is caused by an increased oestrogen:androgen ratio, which can result from germ-cell or Leydig cell tumours. Other potential causes, such as obesity, undescended testis, or prolactinoma, are less likely in this clinical scenario.
Testicular cancer is a common type of cancer that affects men between the ages of 20 and 30. The majority of cases (95%) are germ-cell tumors, which can be further classified as seminomas or non-seminomas. Non-germ cell tumors, such as Leydig cell tumors and sarcomas, are less common. Risk factors for testicular cancer include infertility, cryptorchidism, family history, Klinefelter’s syndrome, and mumps orchitis. Symptoms may include a painless lump, pain, hydrocele, and gynaecomastia.
Tumour markers can be used to diagnose testicular cancer. For germ cell tumors, hCG may be elevated in seminomas, while AFP and/or beta-hCG are elevated in non-seminomas. LDH may also be elevated in germ cell tumors. Ultrasound is the first-line diagnostic tool.
Treatment for testicular cancer depends on the type and stage of the tumor. Orchidectomy, chemotherapy, and radiotherapy may be used. Prognosis is generally excellent, with a 5-year survival rate of around 95% for Stage I seminomas and 85% for Stage I teratomas.
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This question is part of the following fields:
- Renal System
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Question 75
Incorrect
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A 68-year-old man visits the clinic with a complaint of persistent hiccups that have been ongoing for 5 days. During the consultation, he mentions feeling increasingly fatigued over the past 7 months. Apart from these issues, he reports no other health concerns. After conducting some blood tests, you discover that he is experiencing renal failure, and his potassium levels are at 6.2 (normal range is 3.5-5 mmol/l). You urgently advise him to go to the hospital, and upon arrival, the medical team requests an ECG to check for signs of hyperkalaemia. What is an ECG indication of hyperkalaemia?
Your Answer:
Correct Answer: Wide QRS complexes
Explanation:Hyperkalaemia can be identified on an ECG by the presence of broad QRS complexes, which may appear bizarre and form a sinusoidal waveform. Other signs include tall-tented T waves and small or absent P waves. Asystole can also occur as a result of hyperkalaemia.
On the other hand, hypokalaemia can be identified by ECG signs such as small or inverted T waves, ST segment depression, and prominent U waves. A prolonged PR interval and long QT interval may also be present, although a short PR interval may suggest pre-excitation or an AV nodal rhythm.
In the case of a patient presenting with hiccups, persistent hiccups may indicate uraemia, which can be caused by renal failure. Fatigue is another common symptom of renal failure, which is also a common cause of hyperkalaemia.
Hyperkalaemia is a condition where there is an excess of potassium in the blood. The levels of potassium in the plasma are regulated by various factors such as aldosterone, insulin levels, and acid-base balance. When there is metabolic acidosis, hyperkalaemia can occur as hydrogen and potassium ions compete with each other for exchange with sodium ions across cell membranes and in the distal tubule. The ECG changes that can be seen in hyperkalaemia include tall-tented T waves, small P waves, widened QRS leading to a sinusoidal pattern, and asystole.
There are several causes of hyperkalaemia, including acute kidney injury, drugs such as potassium sparing diuretics, ACE inhibitors, angiotensin 2 receptor blockers, spironolactone, ciclosporin, and heparin, metabolic acidosis, Addison’s disease, rhabdomyolysis, and massive blood transfusion. Foods that are high in potassium include salt substitutes, bananas, oranges, kiwi fruit, avocado, spinach, and tomatoes.
It is important to note that beta-blockers can interfere with potassium transport into cells and potentially cause hyperkalaemia in renal failure patients. In contrast, beta-agonists such as Salbutamol are sometimes used as emergency treatment. Additionally, both unfractionated and low-molecular weight heparin can cause hyperkalaemia by inhibiting aldosterone secretion.
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This question is part of the following fields:
- Renal System
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