Which medication is a loop diuretic commonly associated with hypokalemia?

Which medication is a loop diuretic commonly associated with hypokalemia?

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

Answer: (D)

Loop diuretics cause potassium wasting by blocking the Na+-K+-2Cl− cotransporter in the thick ascending limb of the loop of Henle. This stops reabsorption of Na, K, and Cl, so more sodium reaches the collecting duct. The increased Na reabsorption there, driven by aldosterone, promotes potassium secretion into the urine, leading to hypokalemia. Furosemide is the classic loop diuretic, so it’s the medication most commonly linked to low potassium levels. Spironolactone, by contrast, is potassium-sparing and reduces potassium loss. Hydrochlorothiazide can also cause hypokalemia, but its effect is generally milder than a loop diuretic. Acetazolamide can cause shifts in bicarbonate and occasionally potassium, but its primary impact isn’t the pronounced potassium wasting seen with loop diuretics.

Loop diuretics cause potassium wasting by blocking the Na+-K+-2Cl− cotransporter in the thick ascending limb of the loop of Henle. This stops reabsorption of Na, K, and Cl, so more sodium reaches the collecting duct. The increased Na reabsorption there, driven by aldosterone, promotes potassium secretion into the urine, leading to hypokalemia. Furosemide is the classic loop diuretic, so it’s the medication most commonly linked to low potassium levels.

Spironolactone, by contrast, is potassium-sparing and reduces potassium loss. Hydrochlorothiazide can also cause hypokalemia, but its effect is generally milder than a loop diuretic. Acetazolamide can cause shifts in bicarbonate and occasionally potassium, but its primary impact isn’t the pronounced potassium wasting seen with loop diuretics.