Parathormone-Like Effect of Magnesium Replenishment in Steatorrhea

Five of nine patients with intestinal malabsorption had tetany associated with hypomagnesemia, hypocalcemia and absence of demonstrable bone disease. Apparent failure of parathyroid response was suggested by normal or low values for serum alkaline phosphatase and renal phosphate clearance. Intramuscular magnesium therapy abolished tetany in all. In two subjects with severe magnesium depletion there was a coincident rise in serum calcium, phosphate clearance and (in one case) alkaline phosphatase. Infusion of parathyroid extract in the magnesium-depleted state resulted in increased phosphaturia but without a rise in serum calcium. After magnesium repletion, both phosphaturic and calcemic effects were seen. The results are consistent either with failure of parathormone secretion during magnesium depletion or with a reversible resistance of bone to parathormone action.