Captopril and Increased Serum Potassium Levels

To the Editor.— Captopril can cause an increase in serum potassium levels, particularly when coadministered with a potassium supplement.1I would like to describe what appears to be a captopril-induced increase in serum potassium level in a patient receiving a substitute. Report of a Case.— A 59-year-old man was admitted to the hospital for treatment of an acute exacerbation of congestive heart failure and hypertension. His serum potassium level on admission was 4.3 mEq/L. In addition to oral nitrates and furosemide, the patient started therapy with captopril, 12.5 mg every eight hours. Serum potassium determinations over the next several days showed a small but steady increase in serum levels of this electrolyte. A review of the patient's chart showed that he had been instructed to follow a salt-restricted diet. The patient stated that he had been watching his salt and that he had been using a substitute.