A 38-year-old woman has episodic hypertension, headache, and palpitations. 24-hour urine metanephrines are markedly elevated. CT abdomen reveals a 4 cm left adrenal mass. Prior to surgical resection, the CORRECT sequence of preoperative pharmacological preparation is:
- A Alpha-blocker first (phenoxybenzamine), then beta-blocker if tachycardia persists ✓
- B Beta-blocker first, then alpha-blocker
- C Combined alpha-beta blocker (labetalol) alone
- D Calcium channel blocker alone is sufficient
Correct answer: A. Alpha-blocker first (phenoxybenzamine), then beta-blocker if tachycardia persists
Explanation
In phaeochromocytoma, alpha-blockade must precede beta-blockade. Giving a beta-blocker first removes the vasodilatory beta-2 effect, leaving unopposed alpha-1 vasoconstriction and precipitating a hypertensive crisis. Phenoxybenzamine (non-competitive alpha-1/alpha-2 blocker) is started 1–2 weeks pre-operatively; a beta-blocker is added only thereafter if reflex tachycardia is problematic. Labetalol has insufficient alpha-selectivity for this purpose.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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