Pharmacology · single question
A patient takes Triamterene and Hydrochlorothiazide. What electrolyte imbalance does this combination PREVENT?
Show answer and explanation
Correct answer: D. Hypokalemia
Hydrochlorothiazide (a thiazide diuretic) causes potassium wasting (hypokalemia). Triamterene is a potassium-sparing diuretic that works on the collecting duct. Together, the combination prevents hypokalemia — the main risk of using thiazides alone. This is a classic combination (e.g., Dyazide) precisely because triamterene counteracts the potassium-lowering effect of HCTZ.
- A. CORRECT. HCTZ alone causes potassium wasting. Triamterene is potassium-sparing, so the combination prevents hypokalemia.
- B. Incorrect. Hyperkalemia is a risk of triamterene alone (or in patients with renal failure), but the combination is specifically designed to normalize potassium — not cause hyperkalemia.
- C. Incorrect. Hypocalcemia is not a primary concern with this combination. Thiazides actually increase calcium reabsorption, so they can mildly raise serum calcium.
- D. Incorrect. Thiazide diuretics can cause mild hypercalcemia (calcium retention), but that is not what this drug combination is designed to prevent.