Which drug class should be avoided in type 4 RTA due to risk of severe hyperkalemia?

Which drug class should be avoided in type 4 RTA due to risk of severe hyperkalemia?

• A. ACE inhibitors
• B. Thiazide diuretics
• C. Insulin
• D. Albuterol

Answer: (A)

In type 4 RTA, the kidney’s ability to excrete potassium is impaired because there is reduced aldosterone activity (either due to hypoaldosteronism or aldosterone resistance). This makes the collecting duct’s potassium secretion and sodium reabsorption less effective, so potassium builds up in the blood. ACE inhibitors block the formation of angiotensin II, which normally stimulates aldosterone release from the adrenal gland. With less angiotensin II, aldosterone falls further, and the already compromised potassium excretion worsens. This combination raises the risk of severe hyperkalemia in type 4 RTA, so ACE inhibitors are the class to avoid in this situation. Thiazide diuretics promote potassium loss by increasing distal sodium delivery and potassium secretion, which would tend to lower potassium rather than raise it. Insulin and albuterol shift potassium into cells, acutely reducing serum potassium rather than increasing it.

In type 4 RTA, the kidney’s ability to excrete potassium is impaired because there is reduced aldosterone activity (either due to hypoaldosteronism or aldosterone resistance). This makes the collecting duct’s potassium secretion and sodium reabsorption less effective, so potassium builds up in the blood.

ACE inhibitors block the formation of angiotensin II, which normally stimulates aldosterone release from the adrenal gland. With less angiotensin II, aldosterone falls further, and the already compromised potassium excretion worsens. This combination raises the risk of severe hyperkalemia in type 4 RTA, so ACE inhibitors are the class to avoid in this situation.

Thiazide diuretics promote potassium loss by increasing distal sodium delivery and potassium secretion, which would tend to lower potassium rather than raise it. Insulin and albuterol shift potassium into cells, acutely reducing serum potassium rather than increasing it.