Which diuretic has a lower potassium loss compared to furosemide?

Spironolactone is classified as a potassium-sparing diuretic, which means it is designed to help retain potassium in the body while promoting diuresis. Unlike furosemide, which is a loop diuretic that often leads to significant potassium loss through increased urinary excretion, spironolactone works by antagonizing the action of aldosterone in the distal nephron. Aldosterone normally promotes sodium retention and potassium excretion; by blocking this effect, spironolactone reduces potassium loss while still facilitating the elimination of sodium and water.

In contrast, hydrochlorothiazide, a thiazide diuretic, can also lead to some potassium loss, although generally less than furosemide. Mannitol, an osmotic diuretic, does not have any effect on potassium retention and causes an increase in urine output without affecting potassium handling significantly one way or the other. Ethanol is not classified as a diuretic and does not have a direct role in potassium management related to diuretic therapy.

Therefore, based on its mechanism of action, spironolactone has a lower potassium loss compared to furosemide, making it the correct answer.