Which medication can lead to hyperkalemia?

Spironolactone is a potassium-sparing diuretic, which means it helps the body retain potassium while excreting sodium and water. This unique mechanism can lead to hyperkalemia, which is an elevated level of potassium in the blood. Spironolactone works by antagonizing aldosterone, a hormone that promotes the excretion of potassium. When aldosterone's action is inhibited, the kidneys retain more potassium, potentially resulting in hyperkalemia, especially in patients with kidney function impairments or those taking other medications that also increase potassium levels.

In contrast, furosemide and hydrochlorothiazide are both diuretics that typically lead to hypokalemia, as they promote the excretion of potassium along with sodium and water. Amlodipine, a calcium channel blocker, does not directly affect potassium levels and is primarily used to treat hypertension and angina. Therefore, among the choices provided, spironolactone stands out as the medication most likely to cause hyperkalemia due to its potassium-sparing effects.