Diuretic treatment and magnesium losses

Therapy with most kinds of diuretics causes increased urinary excretion of both potassium and magnesium and after long term treatment the skeletal muscle content of these ions is reduced. Magnesium is known activator of Na-K-ATP:ase, which provides the energy for the sodium-potassium pump. Thus, lack of magnesium may impair the pumping of sodium out from the cell and potassium into the cell. Three studies are presented which agree with this theory. In one study the correlation between potassium in serum and potassium in muscle was, among other factors, found to be dependent on the content of muscle magnesium. In another study it was found in hypokalemic patients that muscle potassium could not be corrected by potassium supplementation if there was a concomitant magnesium deficiency. In the third study it was found that muscle potassium increased after magnesium infusion but not after potassium infusion.