What is the effect of Spironolactone on potassium levels?

Spironolactone is a potassium-sparing diuretic, which means its primary effect is to decrease potassium excretion in the kidneys. It acts on the distal tubules of the nephron, inhibiting sodium reabsorption while promoting the retention of potassium. This mechanism results in a lower amount of potassium being excreted in the urine, which can lead to increased serum potassium levels, a condition known as hyperkalemia.

This property of spironolactone makes it useful in conditions where potassium retention is beneficial, such as in patients with heart failure or those who are on other medications that cause potassium loss. By providing a way to maintain potassium levels in the body while managing fluid retention or hypertension, spironolactone is effectively balancing the electrolyte levels rather than allowing for their increase in excretion.

Therefore, the correct choice reflects spironolactone's role in decreasing potassium excretion, aligning with its classification as a potassium-sparing diuretic.