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MDC PQE practice questions

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Question 1Medicine

A 58-year-old man with chronic kidney disease has a haemoglobin of 92 g/L, ferritin 210 µg/L and transferrin saturation 14%. What is the most appropriate next step in managing his anaemia?

  1. Start intravenous iron therapy Correct answer.
  2. Start an erythropoiesis-stimulating agent
  3. Transfuse packed red cells
  4. Recheck haemoglobin in six months

Explanation

Functional or absolute iron deficiency is present because transferrin saturation is below 20% with a ferritin below 100–200 µg/L in CKD, and iron must be repleted before an erythropoiesis-stimulating agent can work effectively. Transfusion is reserved for symptomatic severe anaemia or urgent situations, and ESA therapy without adequate iron stores produces a poor response.

Question 2Medicine

Which finding on urinalysis most strongly suggests an intrinsic glomerular cause of haematuria rather than a lower urinary tract source?

  1. Dysmorphic red cells with red cell casts Correct answer.
  2. Gross haematuria with clots
  3. Alkaline urine with triple phosphate crystals
  4. Isolated microscopic haematuria

Explanation

Dysmorphic red cells and red cell casts indicate that red cells have traversed the glomerular basement membrane and been moulded in tubules, which localises bleeding to the glomerulus. Clots and isolated microscopic haematuria are non-specific and can arise anywhere in the tract.

Question 3Medicine

A 34-year-old woman presents with nephrotic syndrome. Biopsy shows diffuse thickening of the glomerular basement membrane with subepithelial immune deposits and spike formation on silver stain. Which antibody is most characteristically associated with this lesion?

  1. Anti-double-stranded DNA antibody
  2. Anti-phospholipase A2 receptor antibody Correct answer.
  3. Anti-neutrophil cytoplasmic antibody
  4. Anti-glomerular basement membrane antibody

Explanation

Subepithelial deposits with basement membrane spikes in a nephrotic adult describe membranous nephropathy, in which anti-phospholipase A2 receptor antibodies are found in the majority of primary cases. Anti-double-stranded DNA indicates lupus nephritis, anti-GBM causes Goodpasture disease, and ANCA relates to pauci-immune vasculitis.

Question 4Medicine

A patient with autosomal dominant polycystic kidney disease asks about measures that slow cyst growth and loss of kidney function. Which intervention has the best supportive evidence for slowing progression in appropriately selected patients?

  1. Strict blood pressure control with agents blocking the renin-angiotensin system Correct answer.
  2. Routine high-dose loop diuretic therapy
  3. Dietary potassium supplementation
  4. Long-term low-dose corticosteroid therapy

Explanation

Blood pressure control, particularly with renin-angiotensin blockade, slows the rate of kidney function decline and reduces cardiovascular risk in ADPKD. Corticosteroids, loop diuretics and potassium supplements have no role in slowing cyst growth and may cause harm.

Question 5Medicine

Which electrolyte and acid-base picture is most typical of advanced chronic kidney disease before dialysis is started?

  1. Hypernatraemia with a metabolic alkalosis
  2. Hyperkalaemia with a high anion gap metabolic acidosis
  3. Hyperkalaemia with a normal anion gap metabolic acidosis Correct answer.
  4. Hypokalaemia with a respiratory alkalosis

Explanation

Failing kidneys retain potassium and hydrogen ions and lose the ability to excrete ammonium, producing hyperkalaemia with a hyperchloraemic normal anion gap acidosis. A high anion gap acidosis would suggest retained unmeasured acids such as uraemic toxins or ketoacids rather than the typical CKD pattern.

Question 6Medicine

A 26-year-old man has recurrent calcium oxalate kidney stones. Which dietary measure is most appropriate to reduce recurrence?

  1. Restrict dietary calcium to below 400 mg daily
  2. Reduce fluid intake to concentrate urine
  3. Increase dietary oxalate-rich foods
  4. Maintain high fluid intake and normal dietary calcium Correct answer.

Explanation

High fluid intake dilutes urine and reduces supersaturation, while normal dietary calcium binds oxalate in the gut and lowers urinary oxalate. Restricting calcium paradoxically increases oxalate absorption and stone risk, and oxalate loading increases crystalluria.

Question 7Medicine

A 62-year-old woman develops oliguria, a rising creatinine and a bland urinary sediment after ten days of treatment with a proton pump inhibitor. Which mechanism best explains this presentation?

  1. Renal artery thrombosis
  2. Acute interstitial nephritis Correct answer.
  3. Acute tubular necrosis from ischaemia
  4. Prerenal hypoperfusion

Explanation

Proton pump inhibitors are a recognised cause of drug-induced acute interstitial nephritis, which classically presents with rising creatinine, sterile pyuria and white cell casts, sometimes with rash, fever or eosinophilia. Prerenal states and ischaemic tubular injury have different histories and sediment findings.

Question 8Medicine

Which parameter is used to quantify the adequacy of a haemodialysis session?

  1. Glomerular filtration rate
  2. Urine protein-to-creatinine ratio
  3. Fractional excretion of sodium
  4. Kt/V Correct answer.

Explanation

Kt/V measures the clearance of urea (K multiplied by treatment time t, divided by urea distribution volume V) and is the standard index of dialysis dose adequacy. The other parameters assess native kidney function or tubular and glomerular handling rather than dialysis clearance.

Question 9Medicine

A patient on continuous ambulatory peritoneal dialysis develops cloudy effluent with abdominal pain and fever. Which organism is the most common cause of this complication?

  1. Mycobacterium tuberculosis
  2. Escherichia coli
  3. Staphylococcus epidermidis Correct answer.
  4. Candida albicans

Explanation

Coagulase-negative staphylococci such as Staphylococcus epidermidis are the commonest cause of peritoneal dialysis peritonitis, usually from skin flora contaminating the connection. Gram-negative organisms, fungi and mycobacteria cause a minority of episodes and often suggest a different mechanism.

Question 10Medicine

A patient with type 2 diabetes and an eGFR of 35 mL/min/1.73 m² has persistent albuminuria despite a maximal dose of an ACE inhibitor. Which addition has been shown to slow progression of diabetic kidney disease in this setting?

  1. A thiazolidinedione
  2. A loop diuretic titrated to weight
  3. A non-steroidal anti-inflammatory drug
  4. A sodium-glucose cotransporter-2 inhibitor Correct answer.

Explanation

SGLT2 inhibitors reduce albuminuria and slow eGFR decline in diabetic kidney disease, including when added to renin-angiotensin blockade. Loop diuretics address volume but not progression, NSAIDs are nephrotoxic, and thiazolidinediones have no proven renal protective effect.

Question 11Medicine

Which feature best distinguishes minimal change disease from focal segmental glomerulosclerosis on clinical grounds before biopsy?

  1. Selective proteinuria and rapid response to corticosteroids Correct answer.
  2. Presence of hypertension at presentation
  3. Elevation of serum creatinine
  4. Degree of peripheral oedema

Explanation

Minimal change disease typically produces highly selective proteinuria with an abrupt onset and a rapid complete response to corticosteroids, whereas FSGS often shows non-selective proteinuria and a slower or incomplete response. Hypertension, oedema and creatinine elevation occur in both and do not discriminate reliably.

Question 12Medicine

A patient with acute kidney injury has a fractional excretion of sodium below 1% while taking a loop diuretic. How should this result be interpreted?

  1. It excludes volume depletion
  2. It indicates a sodium-losing nephropathy
  3. It is unreliable because loop diuretics increase sodium excretion Correct answer.
  4. It confirms intrinsic tubular injury

Explanation

Loop diuretics block sodium reabsorption in the thick ascending limb and raise urinary sodium, so a low fractional excretion of sodium cannot be used to diagnose prerenal states in patients receiving them. Alternative indices such as the fractional excretion of urea are often used instead.

Question 13Medicine

Which finding is most consistent with nephrogenic diabetes insipidus?

  1. Concentrated urine with low serum osmolality
  2. Oliguria with a high urine osmolality
  3. Dilute urine that fails to concentrate after desmopressin Correct answer.
  4. Dilute urine that concentrates after desmopressin

Explanation

In nephrogenic diabetes insipidus the collecting duct does not respond to antidiuretic hormone, so urine remains dilute even after desmopressin administration. Central diabetes insipidus, by contrast, shows urine concentration after desmopressin.

Question 14Medicine

A 45-year-old man has resistant hypertension, spontaneous hypokalaemia and a raised aldosterone-to-renin ratio. What is the most appropriate confirmatory step?

  1. Overnight dexamethasone suppression test
  2. Saline suppression testing Correct answer.
  3. Renal artery duplex ultrasonography
  4. Plasma metanephrines

Explanation

A raised aldosterone-to-renin ratio suggests primary aldosteronism, and confirmatory testing with saline loading demonstrates failure to suppress aldosterone. Renal artery imaging addresses renovascular disease, metanephrines screen for phaeochromocytoma and dexamethasone suppression tests for Cushing syndrome.

Question 15Medicine

Which urinalysis finding is most characteristic of acute tubular necrosis?

  1. Muddy brown granular casts Correct answer.
  2. White cell casts
  3. Broad waxy casts
  4. Red cell casts

Explanation

Muddy brown granular casts represent sloughed tubular epithelial cells and are the classic sediment finding in acute tubular necrosis. Red cell casts indicate glomerulonephritis, white cell casts suggest interstitial nephritis, and broad waxy casts reflect chronic kidney disease.

Question 16Medicine

A 70-year-old man has a serum sodium of 118 mmol/L after several days of poor intake and thiazide use. He is confused but not seizing. What is the most appropriate initial management?

  1. Fluid restriction alone
  2. Oral urea with no monitoring
  3. Hypertonic saline with a controlled correction rate Correct answer.
  4. Rapid correction with normal saline over two hours

Explanation

Severe symptomatic hyponatraemia with confusion warrants hypertonic saline, with the rise in sodium limited to avoid osmotic demyelination. Rapid correction, fluid restriction alone in a symptomatic patient and unmonitored urea are all unsafe.

Question 17Medicine

Which statement about the use of arteriovenous fistulae for haemodialysis is correct?

  1. They are preferred in patients with severe heart failure
  2. They require maturation time and have lower infection rates than catheters Correct answer.
  3. They carry a higher infection risk than tunnelled catheters
  4. They can be used immediately after creation

Explanation

An arteriovenous fistula needs weeks to mature before reliable cannulation but, once functional, has lower infection and thrombosis rates than central venous catheters. Immediate use is not possible, and high-output flow can worsen heart failure.

Question 18Medicine

A patient with nephrotic syndrome from membranous nephropathy is at increased risk of which complication that warrants anticoagulation consideration?

  1. Cerebral venous sinus thrombosis
  2. Renal vein thrombosis Correct answer.
  3. Hepatic vein thrombosis
  4. Portal vein thrombosis

Explanation

Nephrotic syndrome causes urinary loss of antithrombin III and other anticoagulant proteins, and membranous nephropathy carries a particularly high risk of renal vein thrombosis. The other venous territories are not classically associated with nephrotic syndrome in this way.

Question 19Medicine

Which of the following best describes the mechanism of action of sevelamer in chronic kidney disease?

  1. A calcimimetic that increases calcium-sensing receptor sensitivity
  2. A loop diuretic that increases phosphate excretion
  3. A non-calcium phosphate binder that reduces intestinal phosphate absorption Correct answer.
  4. A vitamin D analogue that suppresses parathyroid hormone

Explanation

Sevelamer is a non-calcium-containing polymer that binds dietary phosphate in the gut and lowers serum phosphate without adding a calcium load. Vitamin D analogues, calcimimetics and diuretics act through different mechanisms.

Question 20Medicine

A 30-year-old woman has loin pain, fever and dysuria with a positive urine culture. Which organism is the most common cause of this presentation in a community setting?

  1. Proteus mirabilis
  2. Escherichia coli Correct answer.
  3. Staphylococcus saprophyticus
  4. Enterococcus faecalis

Explanation

Escherichia coli causes the large majority of community-acquired urinary tract infections, including pyelonephritis. Staphylococcus saprophyticus affects young women but is much less frequent, and Proteus and Enterococcus are less common and often linked to stones or instrumentation.

Question 21Medicine

Which pattern of proteinuria suggests overflow proteinuria rather than glomerular disease?

  1. Predominant albuminuria with oedema
  2. Low-molecular-weight proteins with normal albumin excretion Correct answer.
  3. Proteinuria that varies with posture
  4. Nephrotic-range proteinuria with hypoalbuminaemia

Explanation

Overflow proteinuria occurs when excess low-molecular-weight proteins such as light chains are filtered and exceed tubular reabsorptive capacity, with relatively little albumin. Glomerular disease produces predominant albuminuria, and postural proteinuria is a benign orthostatic phenomenon.

Question 22Medicine

Which electrolyte abnormality is most characteristic of tumour lysis syndrome?

  1. Hypomagnesaemia and metabolic alkalosis
  2. Hypokalaemia, hypophosphataemia and hypercalcaemia
  3. Hypernatraemia and hyperchloraemia
  4. Hyperkalaemia, hyperphosphataemia and hypocalcaemia Correct answer.

Explanation

Lysis of malignant cells releases potassium and phosphate, and the excess phosphate binds calcium, producing hypocalcaemia alongside hyperuricaemia. The resulting acute kidney injury from urate and calcium phosphate deposition is the main source of morbidity.

Question 23Medicine

A patient with cirrhosis has ascites, a urine sodium of 4 mmol/L and a serum-ascites albumin gradient of 1.5 g/dL. What is the most appropriate initial pharmacological management?

  1. Large-volume paracentesis without diuretics
  2. Spironolactone with a low-sodium diet Correct answer.
  3. Albumin infusion alone
  4. Intravenous furosemide alone

Explanation

A high serum-ascites albumin gradient with low urinary sodium indicates portal hypertensive ascites with avid sodium retention, treated initially with an aldosterone antagonist plus sodium restriction. Loop diuretics alone are less effective, and albumin or paracentesis alone do not address the underlying sodium retention.

Question 24Medicine

Which mechanism best explains the anaemia of chronic kidney disease in a patient with adequate iron stores?

  1. Chronic blood loss from dialysis filters
  2. Vitamin B12 malabsorption
  3. Haemolysis from mechanical fragmentation
  4. Reduced erythropoietin production by peritubular fibroblasts Correct answer.

Explanation

The kidney produces erythropoietin from peritubular interstitial fibroblasts, and loss of functioning renal mass reduces this production, causing a normocytic normochromic anaemia. Haemolysis, B12 deficiency and blood loss can contribute but are not the principal mechanism.

Question 25Medicine

A patient develops hyperkalaemia of 6.8 mmol/L with peaked T waves and a widened QRS complex. Which intervention should be given first to stabilise the myocardium?

  1. Intravenous sodium bicarbonate
  2. Intravenous insulin with glucose
  3. Intravenous calcium gluconate Correct answer.
  4. Oral sodium polystyrene sulfonate

Explanation

Intravenous calcium salts antagonise the membrane effects of potassium and protect against arrhythmia within minutes, so they are given first when ECG changes are present. Insulin with glucose, binders and bicarbonate lower potassium but do not immediately stabilise the myocardium.

Question 26Medicine

A 58-year-old man with chronic kidney disease stage 4 has a serum bicarbonate of 18 mmol/L and arterial pH of 7.30. Which acid-base disorder does this represent?

  1. Metabolic acidosis with respiratory compensation Correct answer.
  2. Metabolic alkalosis with respiratory compensation
  3. Mixed metabolic acidosis and metabolic alkalosis
  4. Respiratory acidosis with renal compensation

Explanation

In advanced CKD the kidneys fail to excrete hydrogen ions and regenerate bicarbonate, producing a normal anion gap (or mixed) metabolic acidosis. The low bicarbonate with acidemia defines metabolic acidosis, and the low pH drives hyperventilation, which lowers PaCO2 as respiratory compensation.

Question 27Medicine

Which laboratory value is used in the CKD-EPI 2021 equation to estimate glomerular filtration rate in adults?

  1. Serum creatinine and age and sex Correct answer.
  2. Serum cystatin C alone
  3. Serum urea and albumin
  4. 24-hour urine creatinine clearance

Explanation

The 2021 CKD-EPI creatinine equation estimates GFR from serum creatinine, age and sex, and it removed the race coefficient used in earlier versions. Cystatin C can be added to refine estimates but is not the sole input to the standard creatinine equation.

Question 28Medicine

A patient with autosomal dominant polycystic kidney disease asks about extrarenal associations. Which finding is most typically associated with this condition?

  1. Intracranial berry aneurysms Correct answer.
  2. Pulmonary lymphangioleiomyomatosis
  3. Bilateral acoustic neuromas
  4. Retinal detachment from a collagen defect

Explanation

ADPKD is a systemic ciliopathy associated with intracranial berry aneurysms, hepatic and pancreatic cysts, and mitral valve prolapse. Screening for aneurysms is considered in patients with a family history of subarachnoid haemorrhage.

Question 29Medicine

Which urinalysis pattern is most consistent with prerenal azotaemia in a patient who is volume depleted?

  1. Broad waxy casts with a fractional excretion of sodium above 3%
  2. A fixed urine specific gravity of 1.010 with a fractional excretion of sodium above 2%
  3. A high urine specific gravity with a fractional excretion of sodium below 1% Correct answer.
  4. Sterile pyuria with a fractional excretion of sodium below 1%

Explanation

In prerenal states the tubules are intact and avidly reabsorb sodium and water, so urine is concentrated and fractional excretion of sodium is low. A specific gravity near 1.010 with higher sodium excretion suggests tubular injury instead.

Question 30Medicine

Which finding on renal ultrasound most strongly suggests urinary tract obstruction in a patient with acute kidney injury?

  1. Reduced kidney length of 8 cm
  2. Hydronephrosis with dilatation of the collecting system Correct answer.
  3. A simple cortical cyst of 2 cm
  4. Increased cortical echogenicity

Explanation

Obstruction raises pressure upstream of the blockage and dilates the collecting system, producing hydronephrosis on ultrasound. Relief of obstruction is time-critical because prolonged obstruction causes irreversible tubulointerstitial fibrosis.

Question 31Medicine

A patient with chronic kidney disease is prescribed a phosphate binder. Which agent must be taken with meals to be effective?

  1. Calcium acetate Correct answer.
  2. Sodium bicarbonate
  3. Ferrous sulphate
  4. Amlodipine

Explanation

Phosphate binders work in the gut lumen by binding dietary phosphate, so they must be taken with meals to reduce absorption. Calcium acetate is a common binder used for this purpose in CKD.

Question 32Medicine

A patient with nephrotic syndrome develops a swollen, painful leg with a warm and tender calf. Which complication of nephrotic syndrome does this suggest?

  1. Deep vein thrombosis from urinary loss of antithrombin III Correct answer.
  2. Cellulitis from uraemic pruritus
  3. Spontaneous bacterial peritonitis from low IgA
  4. Acute compartment syndrome from hypocalcaemia

Explanation

Nephrotic syndrome causes urinary loss of anticoagulant proteins such as antithrombin III and increased hepatic synthesis of procoagulant factors, producing a hypercoagulable state. Venous thrombosis, including renal vein thrombosis, is a recognised complication.

Question 33Medicine

Which organism is the most common cause of peritonitis complicating peritoneal dialysis?

  1. Mycobacterium tuberculosis
  2. Coagulase-negative Staphylococcus Correct answer.
  3. Escherichia coli
  4. Candida albicans

Explanation

Skin flora, particularly coagulase-negative staphylococci, are the leading cause of peritoneal dialysis peritonitis because they enter via the catheter exit site or during exchanges. Gram-negative and fungal organisms are less common but suggest a more serious source or outcome.

Question 34Medicine

A 34-year-old woman has hypertension, hypokalaemia and a small left kidney with delayed excretion on a captopril renogram. Which diagnosis is most likely?

  1. Renovascular hypertension from fibromuscular dysplasia Correct answer.
  2. Phaeochromocytoma of the adrenal medulla
  3. Cushing syndrome from a pituitary adenoma
  4. Primary hyperaldosteronism from an adrenal adenoma

Explanation

Fibromuscular dysplasia typically affects young women and causes renal artery stenosis, leading to renovascular hypertension and secondary hyperaldosteronism with hypokalaemia. A captopril renogram showing delayed excretion on the affected side supports functionally significant stenosis.

Question 35Medicine

A patient with IgA nephropathy has persistent proteinuria of 1.5 g per day despite blood pressure control. Which treatment is most appropriate to slow progression?

  1. Long-term low-dose prednisolone for all patients
  2. A high-dose loop diuretic
  3. Aminoglycoside antibiotics
  4. An ACE inhibitor or ARB at the maximum tolerated dose Correct answer.

Explanation

Blockade of the renin-angiotensin system reduces intraglomerular pressure and proteinuria and slows progression in proteinuric IgA nephropathy. Other immunosuppressive therapy is reserved for selected patients with progressive disease.

Question 36Medicine

A patient on haemodialysis has a predialysis potassium of 5.9 mmol/L and normal ECG. Which dietary change is most appropriate?

  1. Reduce intake of potassium-rich foods such as bananas and potatoes Correct answer.
  2. Increase intake of dairy products
  3. Increase intake of oranges and tomatoes
  4. Increase intake of salt substitutes

Explanation

Dietary potassium restriction is the first step in managing hyperkalaemia in dialysis patients, along with review of medications and adequate dialysis. Salt substitutes often contain potassium chloride and can worsen hyperkalaemia.

Question 37Medicine

A patient with type 1 diabetes has a serum sodium of 128 mmol/L, glucose of 45 mmol/L and no neurological symptoms. What is the most appropriate first step in managing the sodium?

  1. Give hypertonic saline immediately
  2. Restrict free water and give furosemide
  3. Ignore the glucose and treat as true hyponatraemia
  4. Correct the measured sodium for the degree of hyperglycaemia before acting Correct answer.

Explanation

Hyperglycaemia draws water into the extracellular space and dilutes sodium, so measured sodium underestimates the true value. Correcting for glucose avoids inappropriate treatment of a pseudohyponatraemia.

Question 38Medicine

A patient with a kidney transplant develops a rise in creatinine, fever and graft tenderness three weeks after transplantation. Which diagnosis is most likely?

  1. Acute cellular rejection Correct answer.
  2. Calcineurin inhibitor toxicity
  3. Recurrent IgA nephropathy
  4. Chronic allograft nephropathy

Explanation

Acute cellular rejection typically presents in the first months after transplantation with fever, graft tenderness and rising creatinine. Diagnosis is confirmed by graft biopsy, and treatment involves high-dose corticosteroids.

Question 39Medicine

Which finding best supports a diagnosis of hepatorenal syndrome in a patient with cirrhosis and acute kidney injury?

  1. A fractional excretion of sodium above 2% with muddy brown casts
  2. No improvement in creatinine after two days of albumin infusion and no other cause of kidney injury Correct answer.
  3. A serum creatinine that rises after volume expansion
  4. Proteinuria of 3 g per day with dysmorphic red cells

Explanation

Hepatorenal syndrome is a functional renal failure diagnosed after excluding other causes and after a trial of albumin without response. The urine sediment is typically bland with low sodium excretion.

Question 40Medicine

A patient with chronic kidney disease has a haemoglobin of 95 g/L, ferritin of 250 µg/L and transferrin saturation of 25%. What is the most appropriate next step?

  1. Start oral iron
  2. Transfuse packed red cells
  3. Check vitamin B12 only
  4. Start an erythropoiesis-stimulating agent Correct answer.

Explanation

Iron stores are adequate with a ferritin above 100 µg/L and transferrin saturation above 20%, so the anaemia of CKD can be treated with an erythropoiesis-stimulating agent. Iron should be repleted before starting these agents.

Question 41Medicine

A patient with severe hypercalcaemia from malignancy has a raised PTH-related peptide and normal PTH. Which mechanism explains the hypercalcaemia?

  1. Primary overproduction of PTH
  2. Renal failure with reduced calcium excretion alone
  3. PTH-related peptide increases bone resorption and renal calcium reabsorption Correct answer.
  4. Excess 1,25-dihydroxyvitamin D from granulomas

Explanation

PTH-related peptide mimics PTH at its receptor, increasing bone resorption and distal tubular calcium reabsorption while suppressing endogenous PTH. This is the classic humoral hypercalcaemia of malignancy.

Question 42Medicine

A patient with a history of recurrent calcium phosphate stones has a fasting urine pH of 7.5 and a urinary tract infection with urease-producing organisms. Which stone type is most likely?

  1. Calcium oxalate stone
  2. Uric acid stone
  3. Cystine stone
  4. Struvite stone Correct answer.

Explanation

Urease-producing organisms such as Proteus split urea into ammonia, alkalinising urine and favouring magnesium ammonium phosphate (struvite) stones. These staghorn calculi require complete removal and infection control.

Question 43Medicine

A patient with acute kidney injury has a rising creatinine, a urine sodium of 60 mmol/L and a fractional excretion of sodium of 3%. Which cause is most likely?

  1. Acute tubular necrosis Correct answer.
  2. Glomerulonephritis with nephrotic range proteinuria
  3. Prerenal azotaemia from dehydration
  4. Obstructive uropathy with hydronephrosis

Explanation

Damaged tubules lose the ability to reabsorb sodium, so urine sodium and fractional excretion are high in acute tubular necrosis. Prerenal states instead show avid sodium retention with low fractional excretion.

Question 44Medicine

A patient with CKD stage 5 has a pericardial friction rub and hypotension. Which management step is most urgent?

  1. Oral potassium binders
  2. Restriction of dietary protein
  3. High-dose furosemide alone
  4. Urgent initiation of dialysis Correct answer.

Explanation

Uraemic pericarditis is a medical emergency and an indication for urgent dialysis, because it can progress to tamponade. Pericardiocentesis is reserved for haemodynamic compromise from tamponade.

Question 45Medicine

A patient with nephrogenic systemic fibrosis risk is about to receive a gadolinium-based contrast agent. Which patient factor most increases this risk?

  1. Normal kidney function with eGFR above 90
  2. Isolated microscopic haematuria with normal eGFR
  3. Advanced chronic kidney disease with eGFR below 30 mL/min/1.73 m² Correct answer.
  4. A history of penicillin allergy

Explanation

Gadolinium agents can deposit in tissues when renal clearance is severely impaired, so the risk of nephrogenic systemic fibrosis is highest in advanced CKD, especially with older linear agents. Macrocyclic agents and alternative imaging are preferred in these patients.

Question 46Medicine

A patient with a kidney transplant is started on a calcineurin inhibitor and develops tremor, hyperkalaemia and a rising creatinine. Which mechanism best explains the hyperkalaemia?

  1. Increased gastrointestinal potassium absorption
  2. Reduced aldosterone effect and altered distal sodium delivery Correct answer.
  3. Excess renin release from the graft
  4. Haemolysis from the drug

Explanation

Calcineurin inhibitors cause a type 4 renal tubular acidosis with reduced aldosterone effect and impaired distal potassium secretion, producing hyperkalaemia. They also cause afferent arteriolar vasoconstriction that can raise creatinine.

Question 47Medicine

A patient with autosomal dominant polycystic kidney disease has a rapidly enlarging kidney and gross haematuria after minor trauma. Which complication should be excluded first?

  1. Cyst haemorrhage or rupture Correct answer.
  2. Renal cell carcinoma in a simple cyst
  3. Acute pyelonephritis without cysts
  4. IgA nephropathy

Explanation

Cyst rupture or haemorrhage is a common cause of gross haematuria after minor trauma in ADPKD and usually resolves with conservative management. Imaging is used to exclude other causes if bleeding is persistent or atypical.

Question 48Medicine

A patient with severe hyponatraemia and confusion has a serum sodium of 112 mmol/L. Which approach to correction is safest?

  1. Raise sodium by no more than 8 to 10 mmol/L in the first 24 hours Correct answer.
  2. Use hypertonic saline at a fixed rate regardless of symptoms
  3. Restrict water and give no saline even if seizures occur
  4. Correct to 135 mmol/L within 6 hours

Explanation

Rapid correction of chronic hyponatraemia risks osmotic demyelination, so the rise should be limited to about 8 to 10 mmol/L in 24 hours. Hypertonic saline is reserved for severe symptoms such as seizures, with careful monitoring.

Question 49Medicine

A patient with membranous nephropathy has a positive anti-phospholipase A2 receptor antibody. Which statement about this finding is most accurate?

  1. It indicates the need for immediate plasmapheresis
  2. It supports a primary autoimmune aetiology rather than a secondary cause Correct answer.
  3. It confirms a paraneoplastic cause
  4. It excludes progression to nephrotic syndrome

Explanation

Anti-phospholipase A2 receptor antibodies are highly specific for primary membranous nephropathy and help distinguish it from secondary causes such as malignancy or infection. Antibody levels can also guide monitoring of disease activity.

Question 50Medicine

A patient with severe acute kidney injury has a serum potassium of 7.2 mmol/L with a widened QRS complex. Which intervention should be given first?

  1. Intravenous furosemide
  2. Subcutaneous insulin alone
  3. Intravenous calcium gluconate Correct answer.
  4. Oral sodium polystyrene sulfonate

Explanation

Intravenous calcium stabilises the myocardium within minutes and is the first step when hyperkalaemia causes ECG changes such as a widened QRS. It does not lower potassium, so insulin-glucose and removal strategies follow.