Role of dietary potassium and magnesium in diuretic-treated patients with cardiac insufficiency.

The role of daily dietary intake of potassium and magnesium in the maintenance of potassium balance was studied in 104 digitalized outpatients with chronic cardiac insufficiency receiving 50 mg hydrochlorothiazide twice daily for 6 weeks. The food consumption data were collected once a week by the 24-hour recall method during the 1st, 2nd and 3rd weeks of the investigation. Serum potassium and magnesium values were followed throughout the study, and total body potassium was measured at the end. During the hydrochlorothiazide treatment, potassium and magnesium levels decreased significantly (p less than 0.001). 46% of the patients became hypokalemic (serum potassium less than or equal to 3.5 mmol/l), hypokalemia being more common (64%) in the patients with a concomitant decrease (-0.063 +/- 0.08 mmol/l) in serum magnesium values. Mean intake of potassium and magnesium was 3.4 g and 299 mg in females and 4.2 g and 380 mg in males, respectively. There was no significant difference in the daily intake of potassium and magnesium between the patients becoming hypokalemic and those remaining normokalemic.