Diuretics and the institutional elderly: a case against routine potassium prescribing

In 14 elderly male residents of a veterans' care complex who were receiving diuretic therapy for cardiac failure, oral potassium (K) supplements were withdrawn. Plasma and erythrocyte K levels were measured immediately before and six weeks after withdrawal of the supplements (38 mEq K daily). The controls comprised 19 elderly residents without disease and not taking drugs likely to influence K status. Study subjects and controls were receiving the same diet (average daily K content 100 mEq). After withdrawal of K supplements, the mean plasma K level fell significantly but the mean erythrocyte K level remained unchanged and did not differ from the control values. For a further six weeks after the withdrawal period, 7 subjects were treated with Aldactazide (diuretic hydrochlorothiazide plus K-sparing spironolactone). The plasma K level increased significantly but the erythrocyte K level remained unchanged. It was concluded that, in this setting, diuretic-induced hypokalemia is not necessarily accompanied by intracellular K depletion and that routine prophylaxis with K supplements or K-sparing agents is unnecessary and not without risk. Such therapy should be reserved for patients considered at special risk of K depletion because of known poor dietary intake, advanced liver disease, secondary hyperaldosteronism with renovascular hypertension, gastrointestinal losses, or nondiuretic medication known to affect K status adversely.