Chronic renal failure and magnesium metabolism.

A number of factors affect the concentration and distribution of magnesium in patients with chronic renal failure (CRF). Poor nutritional intake, impaired absorption from the intestine, vomiting, diarrhea, the use of diuretics and acidosis may result in a negative balance. More commonly, accumulation of magnesium may be the consequence of reduced renal excretion. Magnesium concentrations are increased in serum and red cells in CRF patients. Bone concentrations and total body magnesium also appear to be increased; muscle magnesium does not appear to be increased. Use of magnesium hydroxide-containing antacids as phosphate binders in patients with CRF was largely discontinued 2 decades ago after reports described increases in serum magnesium concentrations to toxic levels. More recently, the undesirable effects of aluminum-containing phosphate binders (encephalopathy, osteomalacia) have led several investigators to report favorable experiences using low concentrations of magnesium in dialysate and a combination of magnesium and aluminum-containing antacids, as phosphate binders, while closely monitoring serum magnesium concentrations.