Thirty-eight patients undergoing cardiac surgery who would be receiving oral furosemide postoperatively were randomly assigned to consume potassium-rich foods (diet) or potassium chloride (KCl) pills (medication). The standard KCl dose was equivalent to half the furosemide dose per day (for example, 60 mg/day of furosemide would require 30 mEq/day of supplemental KCl). Patients in the diet group chose their potassium-rich foods from a list that was provided. If a patient's serum potassium level fell below 3.8 mEq/L, the potassium dose was increased to 75% of the furosemide dose. The mean serum potassium concentration on postoperative days 3 and 4 did not differ significantly between groups. The mean length of hospital stay was significantly lower in the diet group than in the medication group (5.0 vs. 6.3 days; p = 0.03). The reason for that reduction was not apparent, and it did not appear to be due to a decrease in the number of gastrointestinal side effects. When asked their preference for method of supplementation, 79% of patients preferred the diet method.

Comment: Potassium supplementation is often necessary for patients treated with thiazide or loop diuretics. Prescription potassium preparations contain highly concentrated potassium salts, which can cause gastrointestinal side effects including gastric ulceration. High-potassium foods are better tolerated than potassium medication (particularly when the patient is given a range of food choices), and they also provide many other beneficial nutrients.