MRCP Part 1 Endocrinology and Nephrology 2 — Questions and Answers
Question 1: A 50-year-old woman presents with lethargy, weight gain, and constipation. TSH is 45 mU/L (normal 0.4-4.0) and free T4 is 4 pmol/L (normal 9-25). Anti-TPO antibodies are strongly positive. What is the most likely diagnosis?
- Hashimoto's thyroiditis (Correct answer)
- Graves' disease
- Toxic multinodular goitre
- Subacute (de Quervain's) thyroiditis
Correct answer: Hashimoto's thyroiditis
Hashimoto's thyroiditis is the commonest cause of hypothyroidism in the UK. The markedly elevated TSH with low free T4 confirms primary hypothyroidism, and strongly positive anti-thyroid peroxidase (anti-TPO) antibodies confirm autoimmune aetiology. Treatment is lifelong levothyroxine.
Question 2: A 45-year-old man presents with episodic headaches, sweating, and palpitations. His blood pressure is 220/130 mmHg. 24-hour urine metanephrines are markedly elevated. What is the diagnosis?
- Phaeochromocytoma (Correct answer)
- Essential hypertension
- Conn's syndrome
- Cushing's syndrome
Correct answer: Phaeochromocytoma
Phaeochromocytoma presents with the classic triad of episodic headaches, sweating, and palpitations with paroxysmal hypertension. Elevated urinary metanephrines confirm catecholamine excess. It must be excluded before any surgery, and alpha-blockade (phenoxybenzamine) must precede beta-blockade to prevent hypertensive crisis.
Question 3: A patient with end-stage renal disease on haemodialysis has a PTH of 85 pmol/L (normal 1.6-6.9), low calcium, and high phosphate. What is this condition called?
- Secondary hyperparathyroidism (renal osteodystrophy) (Correct answer)
- Primary hyperparathyroidism
- Tertiary hyperparathyroidism
- Hypoparathyroidism
Correct answer: Secondary hyperparathyroidism (renal osteodystrophy)
Secondary hyperparathyroidism occurs in CKD due to phosphate retention, reduced 1,25-dihydroxyvitamin D production, and hypocalcaemia. The parathyroid glands respond appropriately by increasing PTH secretion. Management includes phosphate binders, active vitamin D (alfacalcidol), and cinacalcet if refractory.
Question 4: A 25-year-old woman presents with polyuria, polydipsia, and a random plasma glucose of 22 mmol/L. Urine dipstick shows glucose 3+ and ketones 3+. Blood gas shows pH 7.15, bicarbonate 8 mmol/L. What is the initial fluid replacement?
- 0.9% sodium chloride 1 litre over 1 hour (Correct answer)
- 5% dextrose 1 litre over 1 hour
- Hartmann's solution 500 mL over 30 minutes
- 0.45% sodium chloride 1 litre over 2 hours
Correct answer: 0.9% sodium chloride 1 litre over 1 hour
In diabetic ketoacidosis (DKA), initial fluid resuscitation is with 0.9% sodium chloride. The JBDS DKA guideline recommends 1 litre of 0.9% saline over the first hour, followed by a fixed-rate IV insulin infusion at 0.1 units/kg/hour. 5% dextrose is added later when glucose falls below 14 mmol/L.
Question 5: A 55-year-old man with type 2 diabetes has a urine ACR of 8 mg/mmol on two consecutive samples. His blood pressure is 142/88 mmHg. According to NICE, what is the first-line antihypertensive?
- ACE inhibitor (ramipril) (Correct answer)
- Amlodipine
- Bendroflumethiazide
- Doxazosin
Correct answer: ACE inhibitor (ramipril)
NICE recommends an ACE inhibitor (or ARB if not tolerated) as first-line antihypertensive in diabetic patients with microalbuminuria (ACR 3-30 mg/mmol), regardless of age or ethnicity. ACE inhibitors reduce intraglomerular pressure and slow progression of diabetic nephropathy.
Question 6: A patient on lithium for bipolar disorder presents with polyuria and polydipsia. Serum sodium is 148 mmol/L and urine osmolality is 180 mOsm/kg despite fluid restriction. What has lithium caused?
- Nephrogenic diabetes insipidus (Correct answer)
- Cranial diabetes insipidus
- SIADH
- Psychogenic polydipsia
Correct answer: Nephrogenic diabetes insipidus
Lithium is the most common cause of acquired nephrogenic diabetes insipidus. It accumulates in collecting duct cells and inhibits aquaporin-2 expression, rendering the kidney resistant to ADH. This results in inability to concentrate urine, causing polyuria, polydipsia, and hypernatraemia.
MRCP Part 1 Endocrinology and Nephrology 2
A 50-year-old woman presents with lethargy, weight gain, and constipation.
TSH is 45 mU/L (normal 0.4-4.0) and free T4 is 4 pmol/L (normal 9-25).
Anti-TPO antibodies are strongly positive.
What is the most likely diagnosis?