A 55-year-old man with MEN2A syndrome undergoes prophylactic thyroidectomy. Which additional biochemical screening is MOST critical before operating to prevent perioperative crisis?

• A Serum calcitonin level to stage medullary thyroid carcinoma
• B Serum calcium and PTH to diagnose primary hyperparathyroidism
• C Serum gastrin level to exclude Zollinger-Ellison syndrome
• D 24-hour urinary catecholamines or plasma metanephrines to exclude phaeochromocytoma ✓

Explanation

In MEN2A, phaeochromocytoma must be excluded biochemically (plasma fractionated metanephrines or 24-hour urinary catecholamines) before any surgical procedure, as undiagnosed phaeochromocytoma can precipitate a life-threatening hypertensive crisis during anaesthesia and surgery. If phaeochromocytoma is confirmed, it must be resected first, followed by adrenergic blockade preparation. Serum calcium/PTH screening for hyperparathyroidism (also part of MEN2A) is important but not as immediately life-threatening as undiagnosed phaeochromocytoma.

Reference: Bailey & Love's Short Practice of Surgery, 27th ed.

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Written and medically reviewed by the StethoPrep medical team.