Orally administered magnesium has rarely been reported to result in hypermagnesemia because excess magnesium is normally excreted rapidly in the urine. However, enemas and cathartics that contain magnesium57 have been reported to cause hypermagnesemia in patients with apparently normal renal function.

A reduction in the GFR is the most common factor related to elevation in the serum magnesium concentration.2,13 As the GFR falls, so does the clearance of magnesium. Hypermagnesemia is commonly seen when the GFR is <30 mL per minute. The presence of frank magnesium intoxication in these patients is usually associated with the administration of antacids, enemas, or parenterally administered fluids that contain magnesium. Dialy-sates high in magnesium content have also been reported to result in hypermagnesemia. Hypermagnesemia may be seen in acute renal failure. Contributing factors may include azotemia, rhabdomyolysis, acidosis, and magnesium administration.

The parenteral administration of magnesium in patients with normal renal function is uncommonly associated with magnesium intoxication. The treatment of pregnancy-induced hypertension (toxemia of pregnancy) with magnesium salts results in serum magnesium concentrations of 4 to 7 mEq/L as a therapeutic end point. Excessive magnesium administration in these patients could lead to symptomatic magnesium intoxication. Hypermagnesemia also has been reported to occur in the neonates of mothers treated with parenteral magnesium.