MRCP Part 1 Endocrinology & Renal Medicine 2 — Questions and Answers
Question 1: A patient presents with AKI (creatinine 420 µmol/L, previously 85 µmol/L), oliguria, and urine sediment showing muddy brown casts. What is the most likely cause of AKI?
- Pre-renal AKI from dehydration
- Acute tubular necrosis (Correct answer)
- Glomerulonephritis
- Obstructive uropathy
Correct answer: Acute tubular necrosis
Muddy brown granular casts on urine microscopy are pathognomonic of acute tubular necrosis (ATN), caused by ischaemia or nephrotoxins damaging tubular epithelial cells that are shed and form these casts. Pre-renal AKI shows hyaline casts; GN shows red cell casts; obstruction shows few casts.
Question 2: What is the target blood pressure in a patient with CKD and proteinuria (urine ACR >70 mg/mmol) according to NICE guidelines?
- <140/90 mmHg
- <130/80 mmHg (Correct answer)
- <120/75 mmHg
- <150/90 mmHg
Correct answer: <130/80 mmHg
NICE CKD guidelines recommend a target blood pressure of <130/80 mmHg in patients with CKD who have significant proteinuria (ACR ≥70 mg/mmol) or diabetes. ACE inhibitors or ARBs are first-line for CKD with proteinuria due to their nephroprotective effects.
Question 3: A 25-year-old woman presents with haematuria, bilateral renal cysts on ultrasound, and a family history of renal failure. Genetic testing reveals a PKD1 mutation. What is the diagnosis?
- Medullary sponge kidney
- Autosomal dominant polycystic kidney disease (Correct answer)
- Von Hippel-Lindau syndrome
- Tuberous sclerosis
Correct answer: Autosomal dominant polycystic kidney disease
Autosomal dominant polycystic kidney disease (ADPKD) is caused by mutations in PKD1 (chromosome 16, 85% of cases) or PKD2 (chromosome 4). It is the most common inherited kidney disease, presenting with bilateral cysts, haematuria, hypertension, and progressive renal failure.
Question 4: In nephrotic syndrome, which of the following is characteristically NOT seen?
- Proteinuria >3.5 g/day
- Hypoalbuminaemia
- Haematuria (Correct answer)
- Peripheral oedema
Correct answer: Haematuria
Nephrotic syndrome is characterised by heavy proteinuria (>3.5 g/24h), hypoalbuminaemia, oedema, and hyperlipidaemia/lipiduria. Haematuria is NOT a typical feature of pure nephrotic syndrome (it is more characteristic of nephritic syndrome) though it can occasionally co-exist.
Question 5: A patient with IgA nephropathy presents with visible haematuria 24 hours after an upper respiratory tract infection. What is this phenomenon called?
- Post-streptococcal glomerulonephritis
- Synpharyngitic haematuria (Correct answer)
- Buerger's phenomenon
- Orthostattic proteinuria
Correct answer: Synpharyngitic haematuria
Synpharyngitic (or synpharyngeal) haematuria refers to gross haematuria occurring simultaneously with or shortly after (24–72 hours) mucosal infection (typically URTI) in IgA nephropathy. This differs from post-streptococcal GN where haematuria occurs 2–3 weeks after the infection.
Question 6: Which electrolyte abnormality requires urgent treatment to protect the heart in a patient with a potassium of 6.8 mmol/L?
- Sodium bicarbonate infusion
- Intravenous calcium gluconate (Correct answer)
- Salbutamol nebulisers
- Insulin and dextrose infusion
Correct answer: Intravenous calcium gluconate
IV calcium gluconate (or calcium chloride) is the first-line emergency treatment for severe hyperkalaemia with ECG changes. It does not lower potassium but stabilises the cardiac membrane, reducing the risk of fatal arrhythmia within minutes. It should be given while other measures to reduce potassium are prepared.
MRCP Part 1 Endocrinology & Renal Medicine 2
A patient presents with AKI (creatinine 420 µmol/L, previously 85 µmol/L), oliguria, and urine sediment showing muddy brown casts.
What is the most likely cause of AKI?