Intracellular Magnesium Depletion in Chronic Renal Failure

Skeletal-muscle magnesium, estimated as an index of body magnesium store, was significantly lower (p less than 0.05) in 12 patients with advanced chronic renal failure (most of whom showed hypermagnesemia) than in controls matched for sex and age. There is indirect evidence that renal insufficiency sets at a new level the control of magnesium gradient across the cell membrane. Depletion of total-body (intracellular) magnesium was probably due to inadequate intake, as supplied by the modified Giovannetti diet, and impaired absorption, exacerbated by frequent vomiting. Peritoneal dialysis did not contribute greatly to magnesium depletion in the patients. Two patients had clinical features of hypermagnesemia (lethargy, drowsiness, depressed tendon jerks, general flaccidity, relative hypotension and prolonged PR intervals, QRS complexes and QT segments on the electrocardiogram), but no patient had features of magnesium depletion.