MRCP Part 1 Endocrinology and Nephrology — Questions and Answers
Question 1: A 35-year-old woman presents with weight gain, moon face, abdominal striae, and proximal myopathy. Her 24-hour urinary free cortisol is elevated. What is the next most appropriate investigation?
- Overnight dexamethasone suppression test (Correct answer)
- MRI pituitary
- CT adrenals
- ACTH stimulation test (Synacthen test)
Correct answer: Overnight dexamethasone suppression test
After confirming hypercortisolism with elevated urinary free cortisol, the next step is to perform a low-dose (1 mg) overnight dexamethasone suppression test to confirm Cushing's syndrome. Failure to suppress cortisol (<50 nmol/L) confirms the diagnosis. ACTH levels are then measured to determine the cause.
Question 2: A patient with type 2 diabetes has an eGFR of 35 mL/min/1.73m2 and persistent albuminuria (ACR 45 mg/mmol) despite maximal ACE inhibitor therapy. According to NICE, which additional medication should be considered?
- SGLT2 inhibitor (dapagliflozin) (Correct answer)
- Calcium channel blocker
- Alpha-blocker
- Spironolactone
Correct answer: SGLT2 inhibitor (dapagliflozin)
NICE recommends SGLT2 inhibitors (dapagliflozin) for patients with type 2 diabetes and CKD with ACR >=30 mg/mmol, regardless of HbA1c level. The DAPA-CKD trial demonstrated significant renal and cardiovascular benefits. They can be used down to eGFR 15 mL/min for renoprotection.
Question 3: A 28-year-old woman presents with a thyroid nodule. Fine needle aspiration cytology is reported as Thy3f (follicular neoplasm). What is the recommended management?
- Diagnostic hemithyroidectomy (Correct answer)
- Total thyroidectomy
- Radioiodine ablation
- Observation and repeat ultrasound in 6 months
Correct answer: Diagnostic hemithyroidectomy
Thy3f cytology indicates a follicular neoplasm which cannot be distinguished from follicular carcinoma on cytology alone — capsular and vascular invasion can only be assessed on histological examination. Diagnostic hemithyroidectomy is recommended to obtain a definitive tissue diagnosis.
Question 4: A patient presents with severe hypercalcaemia (corrected calcium 3.8 mmol/L) causing confusion and dehydration. What is the most important initial treatment?
- Intravenous 0.9% sodium chloride (Correct answer)
- Intravenous zoledronic acid
- Oral prednisolone
- Calcitonin injection
Correct answer: Intravenous 0.9% sodium chloride
Aggressive IV fluid resuscitation with 0.9% saline is the first priority in severe hypercalcaemia. Patients are typically volume depleted due to hypercalcaemia-induced nephrogenic diabetes insipidus. Rehydration alone can reduce calcium significantly. Bisphosphonates (zoledronic acid) are given once rehydrated but take 2-4 days to work.
Question 5: Which antibody is most specific for type 1 diabetes mellitus?
- Anti-GAD65 antibodies (Correct answer)
- Anti-nuclear antibodies
- Anti-smooth muscle antibodies
- Anti-thyroid peroxidase antibodies
Correct answer: Anti-GAD65 antibodies
Anti-glutamic acid decarboxylase (anti-GAD65) antibodies are the most commonly tested and most persistent autoantibodies in type 1 diabetes. Other relevant antibodies include IA-2 antibodies and zinc transporter 8 (ZnT8) antibodies. They are useful for confirming autoimmune aetiology, particularly in LADA (latent autoimmune diabetes in adults).
Question 6: A 60-year-old man with CKD stage 4 has a potassium of 6.8 mmol/L. ECG shows tall tented T waves but no QRS broadening. After IV calcium gluconate, what is the next most appropriate treatment to lower potassium?
- Insulin-dextrose infusion (10 units actrapid in 50 mL 50% glucose) (Correct answer)
- Oral calcium resonium
- IV sodium bicarbonate alone
- Oral furosemide
Correct answer: Insulin-dextrose infusion (10 units actrapid in 50 mL 50% glucose)
After cardioprotection with calcium gluconate, insulin-dextrose infusion is the fastest way to shift potassium intracellularly. 10 units of short-acting insulin with 50 mL of 50% glucose typically reduces potassium by 0.5-1.0 mmol/L within 15-30 minutes. Blood glucose monitoring is essential to prevent hypoglycaemia.
MRCP Part 1 Endocrinology and Nephrology
A 35-year-old woman presents with weight gain, moon face, abdominal striae, and proximal myopathy.
Her 24-hour urinary free cortisol is elevated.
What is the next most appropriate investigation?