A combination of triamterene and hydrochlorothiazide is ordered for which purpose?

• A. To decrease the serum potassium level
• B. To decrease the glucose level
• C. To increase the glucose level
• D. To increase the serum potassium level

Answer: (D)

Balancing potassium effects when using diuretics. Hydrochlorothiazide promotes potassium loss by increasing sodium delivery to the collecting ducts, which enhances potassium secretion. Triamterene is potassium-sparing; it blocks sodium channels in the collecting ducts, reducing potassium excretion. Using them together leverages this potassium-sparing action to offset the potassium-wasting effect of hydrochlorothiazide, often keeping serum potassium normal or even slightly higher than with hydrochlorothiazide alone. That’s why this combination is ordered to increase the serum potassium level. Be aware of the risk of hyperkalemia, especially in patients with kidney issues or those on other potassium-raising therapies.