Magnesium in disease: a review with special emphasis on the serum ionized magnesium

This review deals with the six main clinical situations related to magnesiu m or one of its fractions, including ionized magnesium: renal disease, hype rtension, preeclampsia, diabetes mellitus, cardiac disease, and the adminis tration of therapeutic drugs. Issues addressed are the physiological role o f magnesium, eventual changes in its levels, and how these best can be moni tored. In renal disease mostly moderate hypermagnesemia is seen; measuring ionized magnesium offers minimal advantage. In hypertension magnesium might be low ered but its measurement does not seem relevant. In the prediction of sever e pre-eclampsia, elevated ionized magnesium concentration may play a role, but no unequivocal picture emerges. Low magnesium in blood may be cause for , or consequence of, diabetes mellitus. No special fraction clearly indicat es magnesium deficiency leading to insulin resistance. Cardiac: diseases ar e related to diminished magnesium levels. During myocardial infarction, ser um magnesium drops. Total magnesium concentration in cardiac cells can be p redicted from levels in sublingual or skeletal muscle cells. Most therapeut ic drugs (diuretics, chemotherapeutics, immunosuppressive agents, antibioti cs) cause hypomagnesemia due to increased urinary loss. It is concluded that most of the clinical situations studied show hypomagne semia due to renal loss, with exception of renal disease. Keeping in mind t hat only 1% of the total body magnesium pool is extracellular, no simple me asurement of the real intracellular situation has emerged; measuring ionize d magnesium in serum has little added value at present.