Potassium and magnesium balance in thiazide-treated cardiac patients with special reference to diet.

Abstract

ABSTRACT. One hundred and four digitalized patients with chronic heart failure (71 females, 33 males, mean age 62 years) earlier treated with diuretics were administered 50 mg hydroclorothiazide b.i.d. for six weeks. Serum potassium and magnesium values and ECG were followed throughout the study. Total body potassium was determined at the end. Serum potassium fell below 3.6 mmoll‐1 in 46% of the patients during the treatment. Hypokalemia (S‐K ≤ 3.5 mmoll‐1) was more common in females, in patients with initially low potassium values and in patients with a simultaneous concomitant decrease in serum magnesium values. The ECG‐changes and symptoms of defective potassium balance were attributable to serum potassium rather than to total body potassium. There were no differences in total body potassium nor in the daily dietary intake of potassium and magnesium between normokalemic and hypokalemic patients. The daily dietary intake seems sufficient to maintain normokalemia if a patient has no tendency to develop hypokalemia. On the other hand, subjects prone to hypokalemia should be administered potassium supplementation or potassium sparing agents. Some patients seem to require magnesium supplementation, too, in order to maintain their potassium balance.