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  • Question 1 - A 75-year-old man has been diagnosed with glomerulonephritis. He has a medical history...

    Correct

    • A 75-year-old man has been diagnosed with glomerulonephritis. He has a medical history of systemic lupus erythematosus and chronic heart failure. Currently, he is taking statins, paracetamol, ramipril, prednisolone, and verapamil. Which of these medications will need to be discontinued due to his recent diagnosis?

      Your Answer: Ramipril

      Explanation:

      When a patient is experiencing acute kidney injury (AKI), it is important to discontinue certain medications that can exacerbate the condition. These medications include ACE inhibitors/ARBs, NSAIDs, and diuretics, which can all have a negative impact on glomerular filtration rate and pressure. A helpful mnemonic to remember these nephrotoxic drugs is DAMN (Diuretics, ACE inhibitors/ARBs, Metformin, NSAIDs). However, medications such as paracetamol, prednisolone, and statins are usually safe to continue during AKI as they do not significantly affect renal function.

      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.

    • This question is part of the following fields:

      • Renal System
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  • Question 2 - An 85-year-old woman presents with a painful left leg and is diagnosed with...

    Correct

    • An 85-year-old woman presents with a painful left leg and is diagnosed with erysipelas. She is admitted and prescribed penicillin in accordance with trust guidelines. However, after two days of inpatient treatment, the patient becomes anuric and confused. A repeat set of U&Es reveals a significant increase in creatinine levels. What is the probable mechanism by which penicillin caused kidney injury in this elderly patient?

      Your Answer: Acute interstitial nephritis

      Explanation:

      AKI can be caused by penicillin due to its tendency to induce acute interstitial nephritis. This condition is characterized by inflammation in the renal interstitium and is known to occur with various medications, such as NSAIDs, antibiotics, and anticonvulsants. While the other choices may lead to acute kidney injury, they are not typically associated with penicillin antibiotics.

      Acute interstitial nephritis is a condition that is responsible for a quarter of all drug-induced acute kidney injuries. The most common cause of this condition is drugs, particularly antibiotics such as penicillin and rifampicin, as well as NSAIDs, allopurinol, and furosemide. Systemic diseases like SLE, sarcoidosis, and Sjögren’s syndrome, as well as infections like Hanta virus and staphylococci, can also cause acute interstitial nephritis. The histology of this condition shows marked interstitial oedema and interstitial infiltrate in the connective tissue between renal tubules. Symptoms of acute interstitial nephritis include fever, rash, arthralgia, eosinophilia, mild renal impairment, and hypertension. Sterile pyuria and white cell casts are common findings in investigations.

      Tubulointerstitial nephritis with uveitis (TINU) is a condition that typically affects young females. Symptoms of TINU include fever, weight loss, and painful, red eyes. Urinalysis is positive for leukocytes and protein.

    • This question is part of the following fields:

      • Renal System
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  • Question 3 - A 56-year-old presents to his general physician with painless haematuria and is urgently...

    Correct

    • 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: 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.

    • This question is part of the following fields:

      • Renal System
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  • Question 4 - A 75-year-old woman is admitted for a laparoscopic cholecystectomy. As part of her...

    Correct

    • 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: 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.

    • This question is part of the following fields:

      • Renal System
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  • Question 5 - A 65-year-old man visits the haemofiltration unit thrice a week for treatment. What...

    Correct

    • A 65-year-old man visits the haemofiltration unit thrice a week for treatment. What is responsible for detecting alterations in salt concentrations, such as sodium chloride, in normally functioning kidneys and adjusting the glomerular filtration rate accordingly?

      Your Answer: Macula densa

      Explanation:

      The macula densa is a specialized area of columnar tubule cells located in the final part of the ascending loop of Henle. These cells are in contact with the afferent arteriole and play a crucial role in detecting the concentration of sodium chloride in the convoluted tubules and ascending loop of Henle. This detection is affected by the glomerular filtration rate (GFR), which is increased by an increase in blood pressure. When the macula densa detects high sodium chloride levels, it releases ATP and adenosine, which constrict the afferent arteriole and lower GFR. Conversely, when low sodium chloride levels are detected, the macula densa releases nitric oxide, which acts as a vasodilator. The macula densa can also increase renin production from the juxtaglomerular cells.

      Juxtaglomerular cells are smooth muscle cells located mainly in the walls of the afferent arteriole. They act as baroreceptors to detect changes in blood pressure and can secrete renin.

      Mesangial cells are located at the junction of the afferent and efferent arterioles and, together with the juxtaglomerular cells and the macula densa, form the juxtaglomerular apparatus.

      Podocytes, which are modified simple squamous epithelial cells with foot-like projections, make up the innermost layer of the Bowman’s capsule surrounding the glomerular capillaries. They assist in glomerular filtration.

      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.

    • This question is part of the following fields:

      • Renal System
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  • Question 6 - A 49-year-old man with recently diagnosed hypertension has a left adrenal gland phaeochromocytoma...

    Correct

    • A 49-year-old man with recently diagnosed hypertension has a left adrenal gland phaeochromocytoma and is scheduled for a laparoscopic left adrenalectomy. Which of the following structures is not directly associated with the left adrenal gland?

      Your Answer: Lesser curvature of the stomach

      Explanation:

      The left adrenal gland is slightly bigger than the right and has a crescent shape. Its concave side fits against the medial border of the upper part of the left kidney. The upper part is separated from the cardia of the stomach by the peritoneum of the omental bursa. The lower part is in contact with the pancreas and splenic artery and is not covered by peritoneum. On the front side, there is a hilum where the suprarenal vein comes out. The gland rests on the kidney on the lateral side and on the left crus of the diaphragm on the medial side.

      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.

    • This question is part of the following fields:

      • Renal System
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  • Question 7 - A 32-year-old male is undergoing renal transplant surgery. Shortly after the donor kidney...

    Correct

    • A 32-year-old male is undergoing renal transplant surgery. Shortly after the donor kidney has been inserted, the transplanted organ begins to lose its color and becomes limp. Is hyperacute transplant rejection the likely cause of this? What is the underlying mechanism behind it?

      Your Answer: Pre-existing recipient antibodies against donor HLA/ABO antigens

      Explanation:

      Hyperacute transplant rejection is a rapid rejection of a donor organ that can occur within minutes to hours after transplantation. This rejection is caused by pre-existing antibodies against ABO or HLA antigens in the donor organ. If the rejection is widespread, it can activate the coagulation cascade and lead to occlusive thrombosis of the donated organ. Donor organs are carefully matched to recipients to minimize the risk of rejection.

      Mast cell degranulation is an allergic reaction that is mediated by IgE and results in the release of histamine.

      Acute rejection occurs days to weeks after transplantation and is an inflammatory process against the donated organ. Immunosuppressives can be used to slow down this process.

      Chronic rejection occurs months to years after transplantation and is characterized by atrophy of the organ and arteriosclerosis, rather than acute inflammatory processes.

      Graft vs Host disease occurs when donor T-cells mount a cell-mediated response against host tissues. This can lead to cholestasis, jaundice, a widespread rash, and diarrhea. It typically occurs within the first year following transplantation.

      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.

    • This question is part of the following fields:

      • Renal System
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  • Question 8 - A 30-year-old man presents to the emergency department with complaints of abdominal pain,...

    Correct

    • A 30-year-old man presents to the emergency department with complaints of abdominal pain, nausea, and vomiting for a few hours. He has a history of type 1 diabetes mellitus, which is managed with insulin. He admits to running out of his insulin a few days ago. On examination, his temperature is 37.8ºC, pulse is 120/min, respirations are 25/min, and blood pressure is 100/70 mmHg. Dry mucous membranes are noted, and he has a fruity odour on his breath.

      The following laboratory results are obtained:

      Hb 142 g/L Male: (135-180)
      Female: (115 - 160)
      Platelets 250 * 109/L (150 - 400)
      WBC 11.2 * 109/L (4.0 - 11.0)
      Na+ 138 mmol/L (135 - 145)
      K+ 5.2 mmol/L (3.5 - 5.0)
      Urea 2.8 mmol/L (2.0 - 7.0)
      Creatinine 110 µmol/L (55 - 120)
      Glucose 28 mmol/L (4 - 7)

      Which of the following laboratory findings is most likely to be seen in this patient?

      Your Answer: PH 7.1; pCO2 2.3 kPa; Anion Gap 21

      Explanation:

      The patient is experiencing diabetic ketoacidosis, which results in a raised anion gap metabolic acidosis. To determine the correct answer, we must eliminate options with a normal or raised pH (7.4 and 7.5), as well as those with respiratory acidosis (as the patient has an increased respiratory rate and should have a low pCO2). The anion gap is also a crucial factor, with a normal range of 3 to 16. Therefore, the correct option is the one with an anion gap of 21.

      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.

    • This question is part of the following fields:

      • Renal System
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  • Question 9 - An 80-year-old woman arrives at the emergency department with complaints of palpitations. She...

    Correct

    • An 80-year-old woman arrives at the emergency department with complaints of palpitations. She denies any history of cardiac issues or chest pain. Upon conducting an ECG, you observe small P waves and tall tented T waves. You suspect hyperkalaemia and urgently order a blood test to measure her potassium levels. What could be a potential cause of hyperkalaemia?

      Your Answer: Renal failure

      Explanation:

      Renal failure is the correct answer. The kidneys play a crucial role in maintaining potassium balance in the body by regulating potassium intake and excretion. When renal failure occurs, the excretion of potassium is disrupted, leading to hyperkalaemia.

      On the other hand, vomiting and diarrhoea can cause hypokalaemia.

      Alkalosis is characterized by a high serum pH. In this condition, the reduced number of hydrogen ions entering the cell results in less potassium leaving the cell, which can lead to hypokalaemia.

      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.

    • This question is part of the following fields:

      • Renal System
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  • Question 10 - A patient in his 50s becomes dehydrated, resulting in increased water absorption in...

    Correct

    • A patient in his 50s becomes dehydrated, resulting in increased water absorption in the collecting duct. If the concentration of his urine is measured, it would be around 1200mOsm/L. At which point in the nephron would a comparable osmolarity be observed?

      Your Answer: The tip of the Loop of Henle

      Explanation:

      The Loop of Henle creates the highest osmolarity in the nephron, while the proximal tubule absorbs most of the water. The tip of the papilla has the greatest osmolarity, which is also the maximum osmolarity that urine can attain after water absorption in the collecting ducts. The medulla of the kidney facilitates water reabsorption in the collecting ducts due to the osmotic gradient formed by the Loops of Henle.

      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.

    • This question is part of the following fields:

      • Renal System
      7.6
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  • Question 11 - A 68-year-old male presents with a 6-month history of polyuria and polydipsia. He...

    Incorrect

    • A 68-year-old male presents with a 6-month history of polyuria and polydipsia. He has a medical history of hypertension, bipolar disorder, and osteoarthritis, and is currently taking naproxen, ramipril, amlodipine, and lithium. His HbA1c level is 41 mmol/mol. A water deprivation test is performed, and the pre-test urine osmolality is 210 mOsm/kg (500-850), while the post-test urine osmolality is 240 mOsm/kg (500-850). Based on the likely diagnosis, which anatomical location has been affected?

      Your Answer: Proximal convoluted tubule

      Correct Answer: Collecting duct

      Explanation:

      Lithium use in patients can lead to diabetes insipidus by desensitizing the kidney’s response to ADH in the collecting ducts. This is likely the cause of diabetes insipidus in the patient described, as they are on lithium and have no signs of cranial diabetes insipidus. Cranial diabetes insipidus typically results from head trauma or pituitary surgery, while nephrogenic diabetes insipidus is caused by kidney dysfunction.

      The posterior pituitary gland releases ADH, and dysfunction at this site can cause cranial diabetes insipidus. An anterior pituitary tumor may present with bilateral hemianopia, as this gland secretes several hormones.

      Thiazide diuretics act on the distal convoluted tubule and are used to treat diabetes insipidus. Gitelman syndrome is caused by a mutation in the Na+-Cl− co-transporter, while Fanconi syndrome results from dysfunction in the proximal renal tubule, leading to an inability to absorb certain substances.

      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.

    • This question is part of the following fields:

      • Renal System
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  • Question 12 - A 42-year-old man is admitted to the gastroenterology ward with a flare-up of...

    Correct

    • 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: 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.

    • This question is part of the following fields:

      • Renal System
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  • Question 13 - A 20-year-old male presents with lethargy and heavy proteinuria on urinalysis. The consultant...

    Correct

    • 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: 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.

    • This question is part of the following fields:

      • Renal System
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  • Question 14 - Which one of the following changes are not typically seen in established dehydration?...

    Correct

    • Which one of the following changes are not typically seen in established dehydration?

      Your 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.

    • This question is part of the following fields:

      • Renal System
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  • Question 15 - A 6-year-old girl presents to the emergency department with her parents, who are...

    Correct

    • 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: 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.

    • This question is part of the following fields:

      • Renal System
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  • Question 16 - Jill, who is in her mid-30s, has just completed a half marathon and...

    Correct

    • Jill, who is in her mid-30s, has just completed a half marathon and is now dehydrated. The decreased perfusion pressure in her kidneys is detected by baroreceptors, leading to the activation of the renin-angiotensin-aldosterone system (RAAS). As a result, renin cleaves angiotensinogen to angiotensin I, which is then converted to angiotensin II by angiotensin-converting enzyme (ACE). What effect does angiotensin II have on the arteriole that branches off from the renal artery and carries blood away from the glomerulus? And how does this impact Jill's glomerular filtration rate (GFR)?

      Your Answer: Vasoconstriction - increases GFR

      Explanation:

      Angiotensin II causes vasoconstriction of the efferent arteriole, which increases the pressure difference between the afferent and efferent arterioles. This increase in pressure leads to an increase in filtration pressure and thus an increase in GFR. Therefore, efferent arteriole constriction increases GFR.

      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.

    • This question is part of the following fields:

      • Renal System
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  • Question 17 - A 56-year-old man presents to the outpatient cardiology clinic complaining of fatigue and...

    Correct

    • 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: 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.

    • This question is part of the following fields:

      • Renal System
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  • Question 18 - A 9-year-old boy is brought to the hospital by his mother who reports...

    Incorrect

    • A 9-year-old boy is brought to the hospital by his mother who reports that he has been experiencing blood in his urine for the past 3 days, along with a sore throat and fever. The mother states that the boy has been healthy up until this point, with normal development and good performance in school. He was born through a spontaneous vaginal delivery and has never been hospitalized before. The boy has three siblings who are all healthy and doing well in school. During the examination, the doctor notes that the boy has high blood pressure. Blood tests reveal elevated urea levels and protein in a urine sample. If a kidney biopsy were to be performed on this boy, what would be the most likely finding when viewed under light microscopy?

      Your Answer: Thickening of the glomerular basement membrane

      Correct Answer: Proliferation of the mesangial cells

      Explanation:

      If a young child with a history of fever and sore throat develops hematuria and proteinuria, it could be either acute post-streptococcal glomerulonephritis or IgA nephropathy. However, post-streptococcal glomerulonephritis usually presents 2 to 4 weeks after a group A streptococcus infection, while IgA nephropathy presents at the same time as the upper respiratory tract infection. This child has IgA nephropathy, also known as Berger disease (First Aid 2017, p564-566).

      1. Acute post-streptococcal glomerulonephritis is associated with glomerular hypertrophy.
      2. IgA nephropathy involves the proliferation of mesangial cells.
      3. Immune complex deposits in mesangial cells are present in IgA nephropathy but can only be visualized with electron microscopy.
      4. Thickening of the glomerular basement membrane is characteristic of diabetic nephropathy and membranous nephropathy, both types of nephrotic syndrome.
      5. Diabetic nephropathy is associated with an expansion of the mesangial matrix.

      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.

    • This question is part of the following fields:

      • Renal System
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  • Question 19 - A 65-year-old man is having a radical cystectomy for bladder carcinoma. Significant venous...

    Correct

    • A 65-year-old man is having a radical cystectomy for bladder carcinoma. Significant venous bleeding occurs during the surgery. What is the main location for venous drainage from the bladder?

      Your Answer: Vesicoprostatic venous plexus

      Explanation:

      The urinary bladder is surrounded by a complex network of veins that drain into the internal iliac vein. During cystectomy, the vesicoprostatic plexus can be a significant source of venous bleeding.

      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.

    • This question is part of the following fields:

      • Renal System
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  • Question 20 - A 9-year-old boy comes to the GP after experiencing bloody diarrhoea for the...

    Correct

    • A 9-year-old boy comes to the GP after experiencing bloody diarrhoea for the past 6 days. He complains of abdominal pain and has been urinating very little. His mother has also noticed multiple bruises on his body without any known cause. What is the most probable organism responsible for his symptoms?

      Your Answer: E. coli

      Explanation:

      The patient’s symptoms suggest that they may be suffering from haemolytic uraemic syndrome (HUS), which is often caused by an infection with E.coli 0157:H7.

      HUS is characterized by a combination of haemolytic anaemia, thrombocytopaenia, and acute kidney injury, which can ultimately lead to renal failure.

      The presence of bloody diarrhoea in the patient’s medical history is a significant indicator of HUS. Additionally, the reduced urine output is likely due to the acute kidney injury, while the bruising may be a result of the thrombocytopaenia associated with HUS.

      Understanding Haemolytic Uraemic Syndrome

      Haemolytic uraemic syndrome (HUS) is a condition that primarily affects young children and is characterized by a triad of symptoms, including acute kidney injury, microangiopathic haemolytic anaemia, and thrombocytopenia. The most common cause of HUS in children is Shiga toxin-producing Escherichia coli (STEC) 0157:H7, which accounts for over 90% of cases. Other causes of HUS include pneumococcal infection, HIV, systemic lupus erythematosus, drugs, and cancer.

      To diagnose HUS, doctors may perform a full blood count, check for evidence of STEC infection in stool culture, and conduct PCR for Shiga toxins. Treatment for HUS is supportive and may include fluids, blood transfusion, and dialysis if required. Antibiotics are not recommended, despite the preceding diarrhoeal illness in many patients. The indications for plasma exchange in HUS are complicated, and as a general rule, plasma exchange is reserved for severe cases of HUS not associated with diarrhoea. Eculizumab, a C5 inhibitor monoclonal antibody, has shown greater efficiency than plasma exchange alone in the treatment of adult atypical HUS.

      In summary, HUS is a serious condition that primarily affects young children and is characterized by a triad of symptoms. The most common cause of HUS in children is STEC 0157:H7, and diagnosis may involve various tests. Treatment is supportive, and antibiotics are not recommended. The indications for plasma exchange are complicated, and eculizumab may be more effective in treating adult atypical HUS.

    • This question is part of the following fields:

      • Renal System
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  • Question 21 - A 30-year-old female visits her GP complaining of ankle swelling. During the examination,...

    Correct

    • A 30-year-old female visits her GP complaining of ankle swelling. During the examination, her blood pressure is found to be 180/110 mmHg and a urine dipstick reveals protein +++ levels. She is referred to a nephrologist who performs a renal biopsy. The biopsy results show basement membrane thickening on light microscopy and subepithelial spikes on silver staining. Immunohistochemistry confirms the presence of PLA2. What is the probable diagnosis?

      Your Answer: Membranous glomerulonephritis

      Explanation:

      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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      • Renal System
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  • Question 22 - A seven-year-old boy is being investigated for recurrent urinary tract infections. Imaging reveals...

    Correct

    • A seven-year-old boy is being investigated for recurrent urinary tract infections. Imaging reveals abnormal fusion of the inferior poles of both kidneys, leading to a diagnosis of horseshoe kidney. During fetal development, what structure traps horseshoe kidneys as they ascend anteriorly?

      Your Answer: Inferior mesenteric artery

      Explanation:

      During fetal development, horseshoe kidneys become trapped under the inferior mesenteric artery as they ascend from the pelvis, resulting in their remaining low in the abdomen. This can lead to complications such as renal stones, infections, and hydronephrosis, including urteropelvic junction obstruction.

      Understanding Horseshoe Kidney Abnormality

      Horseshoe kidney is a condition that occurs during the embryonic development of the kidneys, where the lower poles of the kidneys fuse together, resulting in a U-shaped kidney. This abnormality is relatively common, affecting approximately 1 in 500 people in the general population. However, it is more prevalent in individuals with Turner’s syndrome, affecting 1 in 20 individuals with the condition.

      The fused kidney is typically located lower than normal due to the root of the inferior mesenteric artery, which prevents the anterior ascent. Despite this abnormality, most people with horseshoe kidney do not experience any symptoms. It is important to note that this condition does not typically require treatment unless complications arise. Understanding this condition can help individuals with horseshoe kidney and their healthcare providers manage any potential health concerns.

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      • Renal System
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  • Question 23 - A 43-year-old man is admitted to the hospital after the nursing staff reported...

    Correct

    • A 43-year-old man is admitted to the hospital after the nursing staff reported a sudden deterioration in his vital signs. Upon assessment, it is discovered that he is suffering from elevated intracranial pressure due to hydrocephalus. The medical team decides to administer mannitol, an osmotic diuretic, to alleviate the condition.

      What is the primary site of action for mannitol in reducing intracranial pressure?

      Your Answer: Tip of the papilla of the Loop of Henle

      Explanation:

      Where is the osmolarity highest in the nephrons of the kidneys, and why is this relevant to the effectiveness of mannitol as an osmotic diuretic?

      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.

    • This question is part of the following fields:

      • Renal System
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  • Question 24 - John, 72-years-old, visits his GP with concerns of frequent urination accompanied by a...

    Incorrect

    • 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: Central zone

      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.

    • This question is part of the following fields:

      • Renal System
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  • Question 25 - A 33-year-old individual presents to the emergency department in an intoxicated state after...

    Correct

    • A 33-year-old individual presents to the emergency department in an intoxicated state after a night of drinking. Although there are no immediate medical concerns, the patient is visibly under the influence of alcohol, exhibiting unsteady gait, reduced social inhibition, and mild slurring of speech. Additionally, the patient is observed to be urinating frequently.

      What is the probable mechanism behind the increased frequency of urination in this patient?

      Your Answer: Suppression of antidiuretic hormone (ADH) release from the posterior pituitary gland

      Explanation:

      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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      • Renal System
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  • Question 26 - A 42-year-old man visits the clinic complaining of a tickly cough that has...

    Correct

    • 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: 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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      • Renal System
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  • Question 27 - A 75-year-old woman has been diagnosed with hyperaldosteronism. What is the source of...

    Correct

    • A 75-year-old woman has been diagnosed with hyperaldosteronism. What is the source of aldosterone release?

      Your Answer: Zona glomerulosa of the adrenal cortex

      Explanation:

      The production of aldosterone takes place in the zona glomerulosa of the adrenal cortex and its function is to preserve water and sodium.

      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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      • Renal System
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  • Question 28 - A 15-year-old teenage boy comes to see his General Practitioner with swelling in...

    Correct

    • 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: 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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      • Renal System
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  • Question 29 - A 75-year-old male ex-smoker presents to a urologist with a complaint of painless...

    Correct

    • A 75-year-old male ex-smoker presents to a urologist with a complaint of painless haematuria that has been ongoing for 3 weeks. He has experienced a weight loss of 5 kg over the past two months. During an urgent cystoscopy, a suspicious mass is discovered and subsequently biopsied. The histology confirms a transitional cell carcinoma of the bladder. A CT scan of the abdomen and pelvis reveals multiple enlarged lymph nodes. Which lymph node is the most probable site of metastasis?

      Your Answer: Internal and external iliac lymph nodes

      Explanation:

      The external and internal iliac nodes are the main recipients of lymphatic drainage from the bladder, while the testes and ovaries are primarily drained by the para-aortic lymph nodes.

      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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      • Renal System
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  • Question 30 - A 40-year-old man visits his doctor for a routine check-up and is informed...

    Correct

    • 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: 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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      • Renal System
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  • Question 31 - A 59-year-old man comes to the GP complaining of lower back pain, weight...

    Correct

    • A 59-year-old man comes to the GP complaining of lower back pain, weight loss, an abdominal mass, and visible haematuria. The GP eliminates the possibility of a UTI and refers him through a 2-week wait pathway. An ultrasound reveals a tumour, and a biopsy confirms renal cell carcinoma. From which part of the kidney does his cancer originate?

      Your Answer: Proximal renal tubular epithelium

      Explanation:

      Renal cell carcinoma originates from the proximal renal tubular epithelium, while the other options, such as blood vessels, distal renal tubular epithelium, and glomerular basement membrane, are all parts of the kidney but not the site of origin for renal cell carcinoma. Transitional cell carcinoma, on the other hand, arises from the transitional cells in the lining of the renal pelvis.

      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.

    • This question is part of the following fields:

      • Renal System
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  • Question 32 - A 38-year-old female visits her doctor complaining of tingling sensations around her mouth...

    Correct

    • A 38-year-old female visits her doctor complaining of tingling sensations around her mouth and frequent muscle cramps. During the blood pressure check, her wrist and fingers start to cramp and flex. Despite these symptoms, she appears to be in good health.

      What condition is the most probable diagnosis?

      Your Answer: Hypocalcaemia

      Explanation:

      Hypocalcaemia is characterized by perioral paraesthesia, cramps, tetany, and convulsions. The female in this scenario is displaying these symptoms, along with a positive Trousseau’s sign and potentially a positive Chvostek’s sign. Hypocalcaemia is commonly caused by hyperparathyroidism, vitamin D deficiency, or phosphate infusions.

      Hyperkalaemia is when there is an elevated level of potassium in the blood, which can be caused by chronic kidney disease, dehydration, and certain medications such as spironolactone. Symptoms may include muscle weakness, heart palpitations, and nausea and vomiting.

      Hypermagnesaemia is rare and can cause decreased respiratory rate, muscle weakness, and decreased reflexes. It may be caused by renal failure, excessive dietary intake, or increased cell destruction.

      Hypokalaemia is relatively common and can cause weakness, fatigue, and muscle cramps. It may be caused by diuretic use, low dietary intake, or vomiting.

      Hyponatraemia may also cause cramps, but typically presents with nausea and vomiting, fatigue, confusion, and in severe cases, seizures or coma. Causes may include syndrome of inappropriate ADH release (SIADH), excessive fluid intake, and certain medications such as diuretics, SSRIs, and antipsychotics.

      Hypocalcaemia: Symptoms and Signs

      Hypocalcaemia is a condition characterized by low levels of calcium in the blood. As calcium is essential for proper muscle and nerve function, many of the symptoms and signs of hypocalcaemia are related to neuromuscular excitability. The most common features of hypocalcaemia include muscle twitching, cramping, and spasms, as well as perioral paraesthesia. In chronic cases, patients may experience depression and cataracts. An electrocardiogram (ECG) may show a prolonged QT interval.

      Two specific signs that are commonly used to diagnose hypocalcaemia are Trousseau’s sign and Chvostek’s sign. Trousseau’s sign is observed when the brachial artery is occluded by inflating the blood pressure cuff and maintaining pressure above systolic. This causes wrist flexion and fingers to be drawn together, which is seen in around 95% of patients with hypocalcaemia and around 1% of normocalcaemic people. Chvostek’s sign is observed when tapping over the parotid gland causes facial muscles to twitch. This sign is seen in around 70% of patients with hypocalcaemia and around 10% of normocalcaemic people. Overall, hypocalcaemia can cause a range of symptoms and signs that are related to neuromuscular excitability, and specific diagnostic signs can be used to confirm the diagnosis.

    • This question is part of the following fields:

      • Renal System
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  • Question 33 - A 44-year-old man presents with a three-week history of leg swelling. He has...

    Correct

    • 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: 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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      • Renal System
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  • Question 34 - A 67-year-old patient is being evaluated after being admitted for treatment of a...

    Correct

    • A 67-year-old patient is being evaluated after being admitted for treatment of a persistent Clostridium difficile infection. The patient had received treatment for a previous infection three weeks ago, but the symptoms did not subside, and she continued to experience diarrhoea. The patient was hospitalized three days ago due to a life-threatening Clostridium difficile infection.

      The patient has been receiving oral vancomycin and IV metronidazole for the past few days, but there has been no improvement in her symptoms. What would be the venous blood gas results in this case?

      Your Answer: Metabolic acidosis + hypokalaemia

      Explanation:

      If a patient experiences prolonged diarrhoea, they may develop metabolic acidosis and hypokalaemia. This is likely the case for a patient with a history of prolonged Clostridium difficile infection, as the loss of bicarbonate ions from the GI tract during diarrhoea can lead to metabolic acidosis. Prolonged diarrhoea can also result in hypokalaemia due to the direct loss of potassium from the GI tract, which the body may be unable to compensate for. Therefore, metabolic acidosis and hypokalaemia are the expected outcomes 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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      • Renal System
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  • Question 35 - At what level is the hilum of the right kidney located? ...

    Correct

    • At what level is the hilum of the right kidney located?

      Your Answer: L1

      Explanation:

      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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      • Renal System
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  • Question 36 - A 54-year-old man visits the clinic after his spouse was diagnosed with hypertension...

    Correct

    • 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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      • Renal System
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  • Question 37 - A 70-year-old male visits his GP complaining of increased difficulty in breathing. He...

    Correct

    • 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: 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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      • Renal System
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  • Question 38 - A 15-year-old boy presents to the ED with severe left flank pain that...

    Correct

    • A 15-year-old boy presents to the ED with severe left flank pain that extends to his groin. He describes his symptoms as 'passing stones,' which he has been experiencing 'since he was a child.' His father also reports having similar issues since childhood. Upon urinalysis, hexagonal crystals are detected, and the urinary cyanide nitroprusside test is positive.

      What is the most probable reason for this patient's condition?

      Your Answer: Amino acid transport abnormality

      Explanation:

      Recurrent kidney stones from childhood and positive family history for nephrolithiasis suggest cystinuria, which is characterized by impaired transport of cystine and dibasic amino acids. The urinary cyanide-nitroprusside test can confirm the diagnosis. Other causes of kidney stones include excess uric acid excretion (gout), excessive intestinal reabsorption of oxalate (Crohn’s disease), infection with urease-producing microorganisms (struvite stones), and primary hyperparathyroidism (calcium oxalate stones).

      Understanding Cystinuria: A Genetic Disorder Causing Recurrent Renal Stones

      Cystinuria is a genetic disorder that causes recurrent renal stones due to a defect in the membrane transport of cystine, ornithine, lysine, and arginine. This autosomal recessive disorder is caused by mutations in two genes, SLC3A1 on chromosome 2 and SLC7A9 on chromosome 19.

      The hallmark feature of cystinuria is the formation of yellow and crystalline renal stones that appear semi-opaque on x-ray. To diagnose cystinuria, a cyanide-nitroprusside test is performed.

      Management of cystinuria involves hydration, D-penicillamine, and urinary alkalinization. These treatments help to prevent the formation of renal stones and reduce the risk of complications.

      In summary, cystinuria is a genetic disorder that causes recurrent renal stones. Early diagnosis and management are crucial to prevent complications and improve outcomes for individuals with this condition.

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      • Renal System
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  • Question 39 - A 54-year-old male comes to the emergency surgical department complaining of intense abdominal...

    Correct

    • A 54-year-old male comes to the emergency surgical department complaining of intense abdominal pain. He has no history of malignancy and is generally healthy. The biochemistry lab contacts the ward with an urgent message that his corrected calcium level is 3.6 mmol/l. What is the preferred medication for treating this abnormality?

      Your Answer: IV Pamidronate

      Explanation:

      Pamidronate is the preferred drug due to its high efficacy and prolonged effects. If using calcitonin, it should be combined with another medication to ensure continued treatment of hypercalcemia after its short-term effects wear off. Zoledronate is the preferred option for cases related to cancer.

      Managing Hypercalcaemia

      Hypercalcaemia can be managed through various methods. The first step is to rehydrate the patient with normal saline, usually at a rate of 3-4 litres per day. Once rehydration is achieved, bisphosphonates can be administered. These drugs take 2-3 days to work, with maximum effect seen at 7 days.

      Calcitonin is another option that can be used for quicker effect than bisphosphonates. In cases of sarcoidosis, steroids may also be used. However, loop diuretics such as furosemide should be used with caution as they may worsen electrolyte derangement and volume depletion. They are typically reserved for patients who cannot tolerate aggressive fluid rehydration.

      In summary, the management of hypercalcaemia involves rehydration with normal saline followed by the use of bisphosphonates, calcitonin, or steroids in certain cases. Loop diuretics may also be used, but with caution. It is important to monitor electrolyte levels and adjust treatment accordingly.

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      • Renal System
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  • Question 40 - A 58-year-old man is having a right nephrectomy. At what level does the...

    Correct

    • 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: 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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      • Renal System
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