A 24-year-old man has severe hypertension (BP 178/112 mmHg) with hypokalemia (K+ 2.7 mEq/L) and metabolic alkalosis. Plasma renin activity is low and plasma aldosterone is LOW. His father required amiloride for lifelong hypertension. Genetic testing shows a gain-of-function mutation of the epithelial sodium channel. The most appropriate therapy is:
- A Spironolactone
- B Captopril
- C Amiloride ✓
- D Hydrochlorothiazide
Correct answer: C. Amiloride
Explanation
Liddle syndrome results from activating mutations of the ENaC subunits, causing unregulated sodium reabsorption with potassium wasting. Renin and aldosterone are both suppressed, distinguishing it from hyperaldosteronism where aldosterone is high. Because the defect is intrinsic channel activation independent of mineralocorticoid receptor signaling, spironolactone is ineffective. Amiloride or triamterene block ENaC directly and correct both the hypertension and hypokalemia. Thiazides would worsen hypokalemia.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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