A nurse is reviewing laboratory results for a client who has heart failure and notes a serum potassium level of 5.2 mEq/L (3.5 to 5.0 mEq/L). Which of the following medications should the nurse withheld?

A. Furosemide: Furosemide is a loop diuretic that promotes potassium excretion. It does not need to be withheld for a mildly elevated potassium level; in fact, it may help lower potassium levels in hyperkalemia. B. Spironolactone: Spironolactone is a potassium-sparing diuretic that can increase serum potassium. With a level of 5.2 mEq/L, administering spironolactone could worsen hyperkalemia and increase the risk of cardiac complications, so the dose should be withheld and the provider notified. C. Metoprolol: Metoprolol, a beta-blocker, does not typically raise potassium levels significantly. While beta-blockers can slightly affect potassium, withholding is not indicated solely based on a potassium level of 5.2 mEq/L. D. Atorvastatin: Atorvastatin, a lipid-lowering agent, has no effect on serum potassium levels and does not need to be withheld in this situation. It can be continued safely.