Management of Potassium Problems During Long-Term Diuretic Therapy

MOST diuretics increase the renal excretion of potassium as part of their pharmacologic action. The thiazides and the loop diuretics (furosemide and ethacrynic acid) have a more pronounced potassium-wasting effect than the mercurials, primarily because they remain effective during continuous long-term therapy, and also because of differences in site and mechanism of action. There is a wide diversity of opinion and there are many unsettled questions regarding the implications of potassium loss during long-term diuretic therapy, the indications for correction, and the best method for offsetting the loss. This commentary will examine the current state of the art. POTASSIUM BALANCE AND DIURETIC THERAPY To maintain potassium homeostasis, the amount of potassium ingested must equal the amount excreted, and under normal conditions, most of the potassium that is lost from the body is excreted in the urine. The regulation of potassium balance by the kidney is closely related to the renal