NEET-PG Medicine Previous Year Questions (2017–2026)

Correct answer: B. Red-cell (RBC) transketolase activity.

The combination of high-output cardiac failure (wet beriberi) with a peripheral neuropathy (dry beriberi) after bariatric surgery points to thiamine (vitamin B1) deficiency, which affects roughly a quarter of patients post-bariatric surgery. The best confirmatory test is the erythrocyte transketolase activity (with the thiamine pyrophosphate effect), as transketolase is a thiamine-dependent enzyme.

Incorrect Options:

• Serum vitamin B12: B12 deficiency gives a macrocytic anaemia and does not cause high-output failure. Vitamin B12.
• 2D echocardiography: may show a high-output state but does not identify the nutritional cause. Echocardiography.
• Nerve conduction study: confirms neuropathy but not its thiamine-related aetiology. Nerve conduction study.

High-Yield Facts:

• Wet beriberi = high-output cardiac failure; dry beriberi = peripheral neuropathy.
• RBC transketolase activity is the confirmatory test for thiamine status.
• Thiamine deficiency is common after bariatric surgery and in alcoholism.
• Treat promptly with thiamine, before glucose in at-risk patients.

Correct answer: A. Hypomagnesaemia.

Magnesium is needed to keep the renal ROMK potassium channels closed. When magnesium is low, this inhibition is lost and potassium is wasted in the urine regardless of how much is replaced, producing refractory hypokalaemia. The fix is to correct magnesium first, after which potassium repletion becomes effective.

Incorrect Options:

• Hyponatraemia: a sodium disorder that does not drive renal potassium wasting. Sodium (as salt).
• Hypocalcaemia: causes tetany and a long QT but does not make hypokalaemia refractory. Calcium.
• Hypermagnesaemia: the opposite state - it tends to depress neuromuscular conduction, not waste potassium. Magnesium (excess is the opposite disorder).

High-Yield Facts:

• Hypomagnesaemia is a classic cause of refractory hypokalaemia.
• Low magnesium opens ROMK channels, increasing renal potassium loss.
• Always correct magnesium before or alongside potassium.
• Both deficiencies can prolong QT and provoke arrhythmias.

Correct answer: Adrenal vein sampling

The picture is confirmed primary aldosteronism (high aldosterone, suppressed renin, non-suppressible on saline loading). Before a unilateral adrenalectomy, aldosterone secretion must be lateralised, and adrenal vein sampling is the gold standard because imaging cannot separate a functioning adenoma from a non-functioning incidentaloma.

Adrenal vein sampling - selective catheterisation lateralises aldosterone hypersecretion.

Incorrect Options:

• Adrenal MRI: good soft-tissue detail but still cannot prove which gland is over-secreting, so it does not settle the management decision.


Adrenal MRI showing a right adenoma - anatomy only, not function.

• MIBG scintigraphy scan: localises catecholamine-secreting tumours (phaeochromocytoma), not aldosterone-producing lesions.


MIBG scan - used for phaeochromocytoma, not aldosteronism.

• CT-guided adrenal biopsy: is not used for aldosteronoma and risks haemorrhage or seeding, adding no functional information.


Core biopsy needle - biopsy has no role in localising aldosteronism.

High-Yield Facts:

• Screen with the plasma aldosterone-to-renin ratio, confirm with a suppression test (saline or fludrocortisone).
• Adrenal vein sampling is the reference standard for lateralisation before unilateral adrenalectomy.
• Unilateral disease (adenoma) is treated surgically, bilateral hyperplasia with a mineralocorticoid-receptor antagonist (spironolactone/eplerenone).
• Spontaneous hypokalaemia with hypertension is a strong clue to primary aldosteronism.