Diuretic-induced magnesium losses.

Long term administration of common loop or distal tubular diuretics may cause somatic magnesium depletion. The resultant deficiency of Mg++ destabilises the myocardium electrically and is a principal cause of cardiac arrhythmias ascribed to diuretics. The adverse effects of diuretics caused by Mg++ depletion can be avoided by selecting diuretics that do not cause magnesium deficiency, minimising the diuretic dose, supplementation of Mg++ intake, or the concomitant use of a K+-retaining, Mg++-sparing diuretic.