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Question 1
Incorrect
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A 57-year-old man with a history of chronic myeloid leukaemia for which he has started receiving chemotherapy presents with left flank pain and oliguria. He has tenderness over his left renal angle. A working diagnosis of kidney stones is made. Both abdominal X-ray and CT scan are unremarkable and no stone is visible.
What is the most likely composition of his kidney stone?Your Answer: Calcium oxalate
Correct Answer: Uric acid
Explanation:Stones formed in the urinary tract due to infections with urease-positive bacteria, such as Proteus mirabilis, are known as struvite stones. These stones are caused by the hydrolysis of urea to ammonia, which alkalizes the urine. Struvite stones often take the shape of staghorn calculi and can be detected through radiography as they are radio-opaque.
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 2
Incorrect
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A 60-year-old man with chronic kidney disease secondary to diabetes is scheduled to undergo a contrast-enhanced CT scan for a suspected brain lesion. His latest eGFR is 51ml/min/1.73m2. After a multidisciplinary team discussion, it was decided that using contrast in the scan was in the patient's best interests, despite the increased risk of contrast-induced acute kidney injury. What would be the most suitable approach to minimize the risk of contrast-induced acute kidney injury in this situation?
Your Answer:
Correct Answer: Offer IV hydration before and after infusion
Explanation:To reduce the risk of contrast-induced acute kidney injury in high-risk patients, NICE guidelines recommend administering sodium chloride at a rate of 1 mL/kg/hour for 12 hours before and after the procedure. While there is some evidence supporting the use of acetylcysteine via IV infusion, it is not strong enough to be recommended in the guidelines. In at-risk patients, it is important to discuss whether the contrast is necessary. Waiting for the patient’s eGFR to improve is not a realistic option in this scenario, as the patient has chronic kidney disease. While maintaining tight glycaemic control is important for long-term kidney function, it is less relevant in this setting. Potentially nephrotoxic medications such as NSAIDs should be temporarily stopped, and ACE inhibitor therapy should be considered for cessation in patients with an eGFR less than 40ml/min/1.73m2, according to NICE guidelines.
Contrast media nephrotoxicity is characterized by a 25% increase in creatinine levels within three days of receiving intravascular contrast media. This condition typically occurs between two to five days after administration and is more likely to affect patients with pre-existing renal impairment, dehydration, cardiac failure, or those taking nephrotoxic drugs like NSAIDs. Procedures that may cause contrast-induced nephropathy include CT scans with contrast and coronary angiography or percutaneous coronary intervention (PCI). Around 5% of patients who undergo PCI experience a temporary increase in plasma creatinine levels of more than 88 µmol/L.
To prevent contrast-induced nephropathy, intravenous 0.9% sodium chloride should be administered at a rate of 1 mL/kg/hour for 12 hours before and after the procedure. Isotonic sodium bicarbonate may also be used. While N-acetylcysteine was previously used, recent evidence suggests it is not effective. Patients at high risk for contrast-induced nephropathy should have metformin withheld for at least 48 hours and until their renal function returns to normal to avoid the risk of lactic acidosis.
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This question is part of the following fields:
- Renal System
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Question 3
Incorrect
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A 70-year-old male visits his GP complaining of increased difficulty in breathing. He has a history of left ventricular heart failure, and his symptoms suggest a worsening of his condition. The doctor prescribes spironolactone as a diuretic. What is the mechanism of action of this medication?
Your Answer:
Correct Answer: Aldosterone antagonist
Explanation:The mechanism of action of spironolactone involves blocking the aldosterone receptor in the distal tubules and collecting duct of the kidneys. In contrast, furosemide acts as a loop diuretic by inhibiting the sodium/potassium/2 chloride inhibitor in the loop of Henle, while acetazolamide functions as a carbonic anhydrase inhibitor.
Spironolactone is a medication that works as an aldosterone antagonist in the cortical collecting duct. It is used to treat various conditions such as ascites, hypertension, heart failure, nephrotic syndrome, and Conn’s syndrome. In patients with cirrhosis, spironolactone is often prescribed in relatively large doses of 100 or 200 mg to counteract secondary hyperaldosteronism. It is also used as a NICE ‘step 4’ treatment for hypertension. In addition, spironolactone has been shown to reduce all-cause mortality in patients with NYHA III + IV heart failure who are already taking an ACE inhibitor, according to the RALES study.
However, spironolactone can cause adverse effects such as hyperkalaemia and gynaecomastia, although the latter is less common with eplerenone. It is important to monitor potassium levels in patients taking spironolactone to prevent hyperkalaemia, which can lead to serious complications such as cardiac arrhythmias. Overall, spironolactone is a useful medication for treating various conditions, but its potential adverse effects should be carefully considered and monitored.
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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 58-year-old man is having a right nephrectomy. At what level does the renal artery typically branch off from the abdominal aorta during this procedure?
Your Answer:
Correct Answer: L2
Explanation:The level with L2 is where the renal arteries typically branch off from the aorta.
Anatomy of the Renal Arteries
The renal arteries are blood vessels that supply the kidneys with oxygenated blood. They are direct branches off the aorta and enter the kidney at the hilum. The right renal artery is longer than the left renal artery. The renal vein, artery, and pelvis also enter the kidney at the hilum.
The right renal artery is related to the inferior vena cava, right renal vein, head of the pancreas, and descending part of the duodenum. On the other hand, the left renal artery is related to the left renal vein and tail of the pancreas.
In some cases, there may be accessory arteries, mainly on the left side. These arteries usually pierce the upper or lower part of the kidney instead of entering at the hilum.
Before reaching the hilum, each renal artery divides into four or five segmental branches that supply each pyramid and cortex. These segmental branches then divide within the sinus into lobar arteries. Each vessel also gives off small inferior suprarenal branches to the suprarenal gland, ureter, and surrounding tissue and muscles.
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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 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:
Correct 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 6
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 7
Incorrect
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A 28-year-old woman with autosomal dominant polycystic kidney disease type 1 is seeking guidance from her general practitioner regarding family planning. She recently lost her father to a subarachnoid haemorrhage, which prompted her to undergo genetic testing to confirm her diagnosis. Despite her desire to start a family with her husband, she is worried about the possibility of passing on the renal disease to her children. On which chromosome is the genetic defect for this condition most commonly found?
Your Answer:
Correct Answer: Chromosome 16
Explanation:The patient’s autosomal dominant polycystic kidney disease type 1 is not caused by a gene on chromosomes 13, 18, or 21. It is important to note that nondisjunction of these chromosomes can lead to other genetic disorders such as Patau syndrome, Edward’s syndrome, and Down’s syndrome. The chance of the patient passing on the autosomal dominant polycystic kidney disease type 1 to her children would depend on the inheritance pattern of the specific gene mutation causing the disease.
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 8
Incorrect
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A 49-year-old woman is having surgery to remove an adrenal adenoma on her left side. During the procedure, the superior adrenal artery is damaged and begins to bleed. What is the origin of this vessel?
Your Answer:
Correct Answer: Inferior phrenic artery
Explanation:The inferior phrenic artery gives rise to the superior adrenal artery.
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 9
Incorrect
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Which one of the following is not a characteristic of the distal convoluted tubule in the kidney?
Your Answer:
Correct Answer: Its secretory function is most effective at low systolic blood pressures (typically less than 100 mmHg)
Explanation:Compartment syndrome can lead to necrosis of the proximal convoluted tubule, which plays a crucial role in reabsorbing up to two thirds of filtered water. Acute tubular necrosis is more likely to occur when systolic blood pressure falls below the renal autoregulatory range, particularly if it is low. However, within this range, the absolute value of systolic BP has minimal impact.
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 10
Incorrect
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A 55-year-old man, who has a history of type 2 diabetes, is prescribed losartan for his hypertension due to the development of a dry cough from ramipril. Losartan works by inhibiting the activity of a substance that acts on the AT1 receptor.
What accurately characterizes the function of this substance?Your Answer:
Correct Answer: Increases filtration fraction through vasoconstriction of the efferent arteriole of the glomerulus to preserve GFR
Explanation:Angiotensin II is responsible for increasing the filtration fraction by constricting the efferent arteriole of the glomerulus, which helps to maintain the glomerular filtration rate (GFR). This mechanism has been found to slow down the progression of diabetic nephropathy. AT1 receptor blockers such as azilsartan, candesartan, and olmesartan can also block the action of Ang II. Desmopressin activates aquaporin, which is mainly located in the collecting duct of the kidneys. Norepinephrine and epinephrine, not Ang II, can cause vasoconstriction of the afferent arteriole of the glomerulus.
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 11
Incorrect
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A 15-year-old teenage boy comes to see his General Practitioner with swelling in his left scrotum. He reports no pain or other symptoms. During examination in a supine position, the GP notes that the left testicle is smaller than the right and there are no abnormal masses on either side. The GP diagnoses the patient with a varicocele, which is caused by increased hydrostatic pressure in the venous plexus of the left scrotum. The question is, where does the left testicular (gonadal) vein drain into?
Your Answer:
Correct Answer: Left renal vein
Explanation:The left renal vein receives drainage from the left testicular vein, while the common iliac and internal iliac veins do not receive any blood from the testicles. The internal iliac veins collect blood from the pelvic internal organs and join the external iliac vein, which drains blood from the legs, to form the common iliac vein. On the other hand, the right testicular vein directly drains into the inferior vena cava since it is situated to the right of the midline. The great saphenous veins, which are located superficially, collect blood from the toes.
Scrotal Problems: Epididymal Cysts, Hydrocele, and Varicocele
Epididymal cysts are the most frequent cause of scrotal swellings seen in primary care. They are usually found posterior to the testicle and separate from the body of the testicle. Epididymal cysts may be associated with polycystic kidney disease, cystic fibrosis, or von Hippel-Lindau syndrome. Diagnosis is usually confirmed by ultrasound, and management is typically supportive. However, surgical removal or sclerotherapy may be attempted for larger or symptomatic cysts.
Hydrocele refers to the accumulation of fluid within the tunica vaginalis. They can be communicating or non-communicating. Communicating hydroceles are common in newborn males and usually resolve within the first few months of life. Non-communicating hydroceles are caused by excessive fluid production within the tunica vaginalis. Hydroceles may develop secondary to epididymo-orchitis, testicular torsion, or testicular tumors. Diagnosis may be clinical, but ultrasound is required if there is any doubt about the diagnosis or if the underlying testis cannot be palpated. Management depends on the severity of the presentation, and further investigation, such as ultrasound, is usually warranted to exclude any underlying cause such as a tumor.
Varicocele is an abnormal enlargement of the testicular veins. They are usually asymptomatic but may be important as they are associated with infertility. Varicoceles are much more common on the left side and are classically described as a bag of worms. Diagnosis is made through ultrasound with Doppler studies. Management is usually conservative, but occasionally surgery is required if the patient is troubled by pain. There is ongoing debate regarding the effectiveness of surgery to treat infertility.
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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 55-year-old man with a medical history of ischaemic heart disease, gout, and diabetes presents with sudden and severe pain in his left renal angle that radiates to his groin. Upon undergoing an urgent CT KUB, it is confirmed that he has nephrolithiasis with hydronephrosis. As a result, he is admitted under the urology team for immediate intervention due to acute kidney injury.
What is the most common material that makes up these calculi in the general population?Your Answer:
Correct Answer: Calcium oxalate
Explanation: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 13
Incorrect
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A 28-year-old rugby player complains of polyuria and polydipsia. He reports being hospitalized 5 months ago due to a head injury sustained while playing rugby. Central diabetes insipidus is confirmed through biochemistry and a water-deprivation test. A pituitary MRI reveals a thickened pituitary stalk, supporting the diagnosis. What is the appropriate medication for this patient?
Your Answer:
Correct Answer: Desmopressin
Explanation:Desmopressin is an effective treatment for central diabetes insipidus, which is a rare condition caused by damage or dysfunction of the posterior pituitary gland resulting in a lack of ADH production. Carbimazole is used to treat hyperthyroidism, while goserelin is used to treat prostate cancer. Indapamide, a thiazide-like diuretic, is used to manage hypertension and heart failure.
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 14
Incorrect
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A 20-year-old man is brought to the Emergency Department in an unconscious state, lying in a pool of blood with several stab wounds in his abdomen. How does the physiological compensatory mechanism differ in the short-term for a venous bleed versus an arterial bleed?
Your Answer:
Correct Answer: A venous bleed causes reduced preload before reducing blood pressure and being detected by baroreceptors whilst an arterial bleed causes an instant blood pressure drop
Explanation:A venous bleed is compensated for in a less direct manner compared to an arterial bleed. The reduction in preload caused by a venous bleed results in a decrease in cardiac output and subsequently, blood pressure. Baroreceptors detect this drop in blood pressure and trigger a physiological compensation response.
In contrast, an arterial bleed causes an immediate drop in blood pressure, which is detected directly by baroreceptors.
Both types of bleeding result in increased levels of angiotensin II and a heightened thirst drive. However, these compensatory mechanisms take longer to take effect than the immediate response triggered by baroreceptors.
Understanding Bleeding and its Effects on the Body
Bleeding, even if it is of a small volume, triggers a response in the body that causes generalised splanchnic vasoconstriction. This response is mediated by the activation of the sympathetic nervous system. The process of vasoconstriction is usually enough to maintain renal perfusion and cardiac output if the volume of blood lost is small. However, if greater volumes of blood are lost, the renin angiotensin system is activated, resulting in haemorrhagic shock.
The body’s physiological measures can restore circulating volume if the source of bleeding ceases. Ongoing bleeding, on the other hand, will result in haemorrhagic shock. Blood loss is typically quantified by the degree of shock produced, which is determined by parameters such as blood loss volume, pulse rate, blood pressure, respiratory rate, urine output, and symptoms. Understanding the effects of bleeding on the body is crucial in managing and treating patients who experience blood loss.
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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 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 16
Incorrect
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A 64-year-old man is seen in the endocrinology clinic for review of his type II diabetes. He is currently on metformin and gliclazide, but his HbA1c is 68 mmol/mol. To improve his glycaemic control, you plan to initiate empagliflozin as a third agent. What is the site of action of this medication to achieve its mechanism of action?
Your Answer:
Correct Answer: Proximal convoluted tubule of the nephron
Explanation:The proximal convoluted tubule of the nephron is where the majority of glucose reabsorption occurs. Empagliflozin, which inhibits the SGLT-2 receptor, prevents glucose reabsorption in this area. Insulin receptors are found throughout the body, not SGLT-2 receptors. The distal convoluted tubule regulates sodium, potassium, calcium, and pH, while the loop of Henle is involved in water resorption. Sulphonylureas act on pancreatic beta cells to increase insulin production and improve glucose metabolism.
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 17
Incorrect
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A 35-year-old woman, gravida 3 para 1, is scheduled for a caesarian-section. During the procedure, it is crucial to avoid damaging certain structures, such as the bladder and its vascular supply, to prevent complications. What is the female bladder's venous drainage structure?
Your Answer:
Correct Answer: Vesicouterine venous plexus
Explanation:The vesicouterine venous plexus is responsible for draining the bladder in females, while the vesicoprostatic venous plexus serves the same function in males by connecting the prostatic venous plexus and vesical plexuses. The pampiniform plexus is responsible for draining the ovaries in females. It is important to note that the terms vesicorectal and vesicovaginal plexuses are not accurate anatomical structures, but rather refer to fistulas that may form between the bladder and nearby structures.
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 18
Incorrect
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A 29-year-old female patient complains of dysuria and frequent urination for the past 3 days. She denies experiencing any vaginal discharge or heavy menstrual bleeding. Upon urine dipstick examination, leukocytes and nitrites are detected. A urine culture reveals the presence of a urease-producing bacteria identified as Proteus mirabilis. The patient is prescribed antibiotics for treatment.
What type of renal stones are patients at risk for developing with chronic and recurrent infections caused by this bacteria?Your Answer:
Correct Answer: Ammonium magnesium phosphate (struvite)
Explanation:The formation of kidney stones is a common condition that involves the accumulation of mineral deposits in the kidneys. This condition is influenced by various risk factors such as low urine volume, dry weather conditions, and acidic pH levels. It is also closely linked to hyperuricemia, which is commonly associated with gout, as well as diseases that involve high cell turnover, such as leukemia.
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 19
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 20
Incorrect
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A 68-year-old man with a history of bladder cancer due to beta-naphthylamine exposure presents with painless haematuria and suprapubic pain. He underwent successful surgical resection for bladder cancer 5 years ago and is now retired as a chemical engineer. The urology team suspects a possible recurrence with locoregional spread. What imaging modality is most suitable for determining the extent of cancer spread in this patient?
Your Answer:
Correct Answer: Pelvic MRI
Explanation:The most effective imaging technique for identifying the locoregional spread of bladder cancer is pelvic MRI.
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 21
Incorrect
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In individuals experiencing abdominal discomfort and nausea, along with recurrent kidney stones and urinary tract infections, what structural anomaly might be detected on imaging?
Your Answer:
Correct Answer: Fused kidneys crossing anterior to the aorta
Explanation:The presence of abdominal pain, nausea, and recurrent kidney stones and urinary tract infections raises the possibility of a horseshoe kidney, where two kidneys are fused in the midline and pass in front of the aorta. This is a congenital condition that is more prevalent in males and is linked to a higher incidence of urinary tract infections. Unfortunately, there is no cure for this condition, and treatment is focused on managing symptoms.
Moreover, the identification of numerous cysts in the kidneys suggests the presence of polycystic kidney disease, which is associated with diverticulosis and cerebral aneurysms.
Understanding the Risk Factors for Renal Stones
Renal stones, also known as kidney stones, are solid masses that form in the kidneys and can cause severe pain and discomfort. There are several risk factors that can increase the likelihood of developing renal stones. Dehydration is a significant risk factor, as it can lead to concentrated urine and the formation of stones. Other factors include hypercalciuria, hyperparathyroidism, hypercalcaemia, cystinuria, high dietary oxalate, renal tubular acidosis, medullary sponge kidney, polycystic kidney disease, and exposure to beryllium or cadmium.
Urate stones, a type of renal stone, are caused by the precipitation of uric acid. Risk factors for urate stones include gout and ileostomy, which can result in acidic urine due to the loss of bicarbonate and fluid.
In addition to these factors, certain medications can also contribute to the formation of renal stones. Loop diuretics, steroids, acetazolamide, and theophylline can promote the formation of calcium stones, while thiazides can prevent them by increasing distal tubular calcium resorption.
It is important to understand these risk factors and take steps to prevent the formation of renal stones, such as staying hydrated, maintaining a healthy diet, and avoiding medications that may contribute to their formation.
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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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At which of the following locations is the highest amount of water absorbed?
Your Answer:
Correct Answer: Jejunum
Explanation:The small bowel, specifically the jejunum and ileum, is the primary location for water absorption in the gastrointestinal tract. While the colon does play a role in water absorption, its contribution is minor in comparison. However, if there is a significant removal of the small bowel, the importance of the colon in water absorption may become more significant.
Water Absorption in the Human Body
Water absorption in the human body is a crucial process that occurs in the small bowel and colon. On average, a person ingests up to 2000ml of liquid orally within a 24-hour period. Additionally, gastrointestinal secretions contribute to a further 8000ml of fluid entering the small bowel. The process of intestinal water absorption is passive and is dependent on the solute load. In the jejunum, the active absorption of glucose and amino acids creates a concentration gradient that facilitates the flow of water across the membrane. On the other hand, in the ileum, most water is absorbed through facilitated diffusion, which involves the movement of water molecules with sodium ions.
The colon also plays a significant role in water absorption, with approximately 150ml of water entering it daily. However, the colon can adapt and increase this amount following resection. Overall, water absorption is a complex process that involves various mechanisms and is essential for maintaining proper hydration levels in the body.
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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 39-year-old male visits his GP for a routine check-up of his high blood pressure. Despite being on a maximum dose of ramipril, amlodipine, and spironolactone, his blood pressure remains consistently at or above 160/100 mmHg. During the consultation, the patient reveals that he has been experiencing episodes of intense anxiety, sweating, palpitations, and fear about twice a week for the past six months.
What is the source of the hormone responsible for the symptoms experienced by this man?Your Answer:
Correct Answer: Adrenal medulla
Explanation:The patient’s symptoms suggest a phaeochromocytoma, which is caused by a tumor in the adrenal medulla that leads to the release of excess epinephrine. This results in refractory hypertension and severe episodes of sweating, palpitations, and anxiety.
While the pituitary gland produces hormones like thyroid-stimulating hormone and adrenocorticotropic hormone, these hormones do not directly cause the symptoms seen in this patient. Additionally, excess ACTH production is associated with Cushing’s syndrome, which does not fit the clinical picture.
The adrenal cortex has three distinct zones, each responsible for producing different hormones. The zona fasciculata produces glucocorticoids like cortisol, which can lead to Cushing’s syndrome. The zona glomerulosa produces mineralocorticoids like aldosterone, which can cause uncontrolled hypertension and electrolyte imbalances. The zona reticularis produces androgens like testosterone. However, none of these conditions match the symptoms seen in this patient.
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 24
Incorrect
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A 30-year-old woman is being evaluated for possible Addison's disease due to experiencing atypical exhaustion and observing a mild bronzing of her skin. The underlying cause is believed to be an autoimmune assault on the adrenal cortex, leading to reduced secretion of aldosterone.
What is the typical physiological trigger for the production of this steroid hormone?Your Answer:
Correct Answer: Angiotensin II
Explanation:The correct answer is Angiotensin II, which stimulates the release of aldosterone. It also has the ability to stimulate the release of ADH, increase blood pressure, and influence the kidneys to retain sodium and water.
Angiotensin I is not the correct answer as it is converted to angiotensin II by ACE and does not have a direct role in the release of aldosterone by the adrenal cortex.
ACE is released by the capillaries in the lungs and is responsible for converting angiotensin I to angiotensin II.
Angiotensinogen is not the correct answer as it is the first step in the renin-angiotensin-aldosterone system. It is released by the liver and converted to angiotensin I by renin.
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 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 26
Incorrect
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A 45-year-old patient presents to the clinic with complaints of abdominal pain. Upon routine blood tests, the following results were obtained:
Na+ 142 mmol/l
K+ 4.0 mmol/l
Chloride 104 mmol/l
Bicarbonate 19 mmol/l
Urea 7.0 mmol/l
Creatinine 112 µmol/l
What is the calculated anion gap?Your Answer:
Correct Answer: 23 mmol/L
Explanation:Understanding Anion Gap in Metabolic Acidosis
Metabolic acidosis is a condition where the body produces too much acid or loses too much bicarbonate. Anion gap is a useful tool in diagnosing metabolic acidosis. It is calculated by subtracting the sum of bicarbonate and chloride from the sum of sodium and potassium. A normal anion gap is between 8-14 mmol/L.
There are two types of metabolic acidosis: normal anion gap and raised anion gap. Normal anion gap or hyperchloraemic metabolic acidosis can be caused by gastrointestinal bicarbonate loss, renal tubular acidosis, drugs like acetazolamide, ammonium chloride injection, and Addison’s disease. On the other hand, raised anion gap metabolic acidosis can be caused by lactate due to shock or hypoxia, ketones in diabetic ketoacidosis or alcohol, urate in renal failure, acid poisoning from salicylates or methanol, and 5-oxoproline from chronic paracetamol use.
Understanding anion gap in metabolic acidosis is crucial in identifying the underlying cause of the condition. It helps healthcare professionals in providing appropriate treatment and management to patients.
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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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Sarah, who is in her 50s, has recently undergone a kidney transplant. A few hours after the surgery, she begins to feel extremely sick, experiencing a fever of 39°C and overall discomfort. She also reports pain at the site of the transplant, and the medical staff have noted a significant decrease in her urine output. The consultant suggests that this could be due to pre-existing antibodies, given the timing of the symptoms.
What is the most probable diagnosis in Sarah's case?Your Answer:
Correct Answer: Hyperacute transplant rejection
Explanation:Based on the symptoms and timeframe, it is likely that the patient is experiencing hyperacute transplant rejection. This type of rejection is classified as a type II hypersensitivity reaction, which occurs when pre-existing IgG or IgM antibodies attack HLA or ABO antigens. This autoimmune response causes thrombosis in the vascular supply to the transplanted organ, leading to ischemia and necrosis. Unfortunately, the only treatment option is to remove the graft.
Acute graft failure, on the other hand, typically occurs over several months and is often caused by HLA mismatch. This condition can be treated with immunosuppressants and steroids.
Chronic graft failure is characterized by antibody- and cell-mediated mechanisms that lead to fibrosis of the transplanted organ over time. This process usually takes more than six months to develop.
Post-transplant acute tubular necrosis is another possible complication that can cause reduced urine output and muddy brown casts on urinalysis. However, it does not typically present with the hyperacute symptoms described above.
Lymphocele is a common post-transplant complication that is usually asymptomatic but can cause a mass and compress the ureter if it becomes large enough. It can be drained through percutaneous or intraperitoneal methods.
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 28
Incorrect
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A 56-year-old man with a history of alcohol excess and type 2 diabetes presents to the emergency department in an intoxicated state. He takes metformin and his recent HbA1c was 44 mmol/mol. On arrival, his blood sugar is 5.1 mmol/L and he frequently needs to urinate. The examination is unremarkable except for his intoxicated state. His blood test shows a creatinine level of 66 µmol/L (55 - 120). What is causing the patient's polyuria?
Your Answer:
Correct Answer: ADH suppression in the posterior pituitary gland
Explanation:Alcohol bingeing can result in the suppression of ADH in the posterior pituitary gland, leading to polyuria.
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 29
Incorrect
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A 33-year-old woman is scheduled for a kidney biopsy following a renal ultrasound that revealed several large cysts on her left kidney. The medical team has informed her of the potential risks associated with the procedure, such as the possibility of puncturing the primary blood vessels that supply the kidney - the renal artery and vein. At what anatomical level do these vessels enter the left kidney, considering their location?
Your Answer:
Correct Answer: L1
Explanation:The correct level for the hilum of the left kidney is L1, which is also where the renal artery, vein, and ureter enter the kidney. T12 is not the correct level as it is the location of the adrenal glands or upper pole of the kidney. L2 is also not correct as it refers to the hilum of the right kidney, which is slightly lower. L4 is not the correct level as both renal arteries come off above this level from the abdominal aorta.
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 30
Incorrect
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A 23-year-old male presents to the emergency department with decreased level of consciousness after a night of excessive alcohol intake. He is observed to have increased urine output. There is no history of substance abuse according to his companions.
What is the probable cause of the patient's polyuria?Your Answer:
Correct Answer: antidiuretic hormone inhibition
Explanation:Alcohol bingeing can result in the suppression of ADH in the posterior pituitary gland, leading to polyuria. This occurs because alcohol inhibits ADH, which reduces the insertion of aquaporins in the collecting tubules of the nephron. As a result, water reabsorption is reduced, leading to polyuria. The other options provided are incorrect because they do not accurately describe the mechanism by which alcohol causes polyuria. Central diabetes insipidus is a disorder of ADH production in the brain, while nephrogenic diabetes insipidus is caused by kidney pathology. Osmotic diuresis occurs when solutes such as glucose and urea increase the osmotic pressure in the renal tubules, leading to water retention, but this is not the primary mechanism by which alcohol causes polyuria.
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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