What effect does an ACE inhibitor (ACEI) have on potassium levels?

ACE inhibitors (ACEIs) are medications commonly used to treat conditions such as hypertension and heart failure. One significant effect of ACEIs is their influence on potassium levels in the body. ACEIs work by inhibiting the angiotensin-converting enzyme, which plays a key role in the renin-angiotensin-aldosterone system (RAAS). This inhibition reduces the production of angiotensin II, a peptide that causes vasoconstriction and stimulates aldosterone secretion from the adrenal glands.

Aldosterone is responsible for promoting the reabsorption of sodium and the excretion of potassium in the kidneys. When ACEIs decrease the levels of angiotensin II and subsequently aldosterone, there is less sodium reabsorption and decreased potassium excretion. As a result, potassium levels can become elevated, leading to hyperkalemia.

This potential for increased potassium levels is particularly important to monitor in patients who may already be at risk for electrolyte imbalances, such as those with kidney dysfunction or those taking other medications that can contribute to hyperkalemia. Therefore, the correct choice is that ACE inhibitors can cause hyperkalemia due to their effect on the balance of sodium and potassium in the renal system.