Plasma magnesium concentration in primary hyperparathyroidism.

The plasma magnesium concentration has been determined in 73 patients with primary hyperparathyroidism. In most patients it lay within the normal range (1.7-2.3 mg./100 ml.), but in five it was less than 1.6 mg./100 ml. These patients had relatively high urinary magnesium outputs, and one of them, studied in greater detail, failed to retain parenterally administered magnesium. Hence hypomagnesaemia in hyperparathyroidism may be associated with a defect in renal magnesium conservation, which may be reversible.