Incidence of Hypomagnesaemia in Intestinal Malabsorption

Abstract

Subnormal serum magnesium levels were found in 15 out of 42 patients suffering from intestinal malabsorption. In most patients hypomagnesaemia was not associated with any specific clinical signs. Patients with levels of less than 1 mEq/l invariably also had hypocalcaemia and tetany, but their tetany was relieved when their serum calcium levels were restored to normal, although the serum magnesium might remain as low as before. Magnesium supplements should be given when the plasma magnesium is below 1 mEq/l. The cause of hypomagnesaemia in these patients was a negative magnesium balance due to intestinal loss of magnesium. Factors influencing magnesium balance are described. In 2 patients with hypomagnesaemia the low serum magnesium levels were found to be associated with a moderate reduction of the Mg/Ca ratio in bone; in 1 there was also a marked reduction in muscle magnesium.