A 22-year-old man has BP 172/106 mmHg, serum potassium 2.8 mEq/L, and metabolic alkalosis. Plasma renin activity is undetectable and plasma aldosterone is very low. His father had hypertension diagnosed in his twenties. Spironolactone produced no improvement in his potassium level. Which is the most appropriate treatment?

• A Amiloride ✓
• B Higher-dose spironolactone
• C Captopril
• D Hydrocortisone replacement

Explanation

Liddle syndrome is caused by gain-of-function mutations of the epithelial sodium channel (ENaC, genes SCNN1B or SCNN1G) inherited autosomal dominantly, causing sodium retention, potassium wasting, suppressed renin, and low aldosterone. Because the defect is in the channel itself rather than mineralocorticoid receptor activation, spironolactone is predictably ineffective. Amiloride blocks ENaC directly and corrects both hypertension and hypokalemia. Captopril fails because renin is already suppressed, and hydrocortisone has no role in this salt-retaining state.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

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Written and medically reviewed by the StethoPrep medical team.