If a patient on furosemide remains clinically fluid-overloaded, what is a common next-step diuretic addition?

• A. Spironolactone
• B. Hydrochlorothiazide
• C. Mannitol
• D. Acetazolamide

Answer: (A)

When a patient with fluid overload continues to have excess volume despite a loop diuretic, the goal is to counteract ongoing aldosterone-driven sodium retention and reduce diuretic resistance. Adding an aldosterone antagonist like spironolactone is a common next step because it blocks mineralocorticoid receptors in the collecting duct, leading to kept sodium from being reabsorbed and reduced potassium loss. This not only enhances diuresis but has been shown to improve survival in heart failure, making it a preferred addition to furosemide in this setting. Monitor potassium and kidney function to avoid hyperkalemia, especially in patients with kidney disease or those on other potassium-sparing meds.

Hydrochlorothiazide can be added for extra diuresis in resistant edema, but it tends to cause potassium loss and lacks the mortality benefit seen with spironolactone. Mannitol is not used for chronic edema in heart failure and can cause volume shifts and electrolyte problems. Acetazolamide isn’t the typical choice for congestive edema and is not as effective in this scenario.