Which of the following is a potassium-sparing diuretic?

Which of the following is a potassium-sparing diuretic?

• A. Spironolactone
• B. Furosemide
• C. Hydrochlorothiazide
• D. Acetazolamide

Answer: (A)

Potassium-sparing diuretics keep potassium in the body by blocking aldosterone’s action in the distal tubule and collecting duct, which reduces sodium reabsorption and water reabsorption while minimizing potassium loss. Spironolactone does this by antagonizing aldosterone receptors, so sodium is excreted with less potassium being lost, effectively preserving potassium while still producing a diuretic effect. Other diuretics do not share this mechanism: furosemide is a loop diuretic that inhibits the Na-K-2Cl transporter in the loop of Henle, leading to more potassium being lost; hydrochlorothiazide is a thiazide that inhibits the Na-Cl transporter in the distal tubule and also promotes potassium excretion; acetazolamide is a carbonic anhydrase inhibitor in the proximal tubule and primarily causes bicarbonate and fluid loss without sparing potassium.

Potassium-sparing diuretics keep potassium in the body by blocking aldosterone’s action in the distal tubule and collecting duct, which reduces sodium reabsorption and water reabsorption while minimizing potassium loss. Spironolactone does this by antagonizing aldosterone receptors, so sodium is excreted with less potassium being lost, effectively preserving potassium while still producing a diuretic effect. Other diuretics do not share this mechanism: furosemide is a loop diuretic that inhibits the Na-K-2Cl transporter in the loop of Henle, leading to more potassium being lost; hydrochlorothiazide is a thiazide that inhibits the Na-Cl transporter in the distal tubule and also promotes potassium excretion; acetazolamide is a carbonic anhydrase inhibitor in the proximal tubule and primarily causes bicarbonate and fluid loss without sparing potassium.