Metabolic balance studies of high calcium intake in osteoporosis

Abstract

Positive calcium balance of varying degree has been induced by high calcium intake in four patients with frank osteoporosis and in one patient with apparently normal bone. Phosphate retention appeared to be less with calcium gluconate supplementation than with addition of dicalcium phosphate (CaHPO 4). There was often modest increase in urinary calcium but not hypercalciuria during high calcium intake, especially during calcium gluconate administration. Slow intravenous administration of calcium gluconate to one patient resulted in marked hypercalciuria. In the normal patient, who showed moderate storage of calcium during dicalcium phosphate supplementation, the laxative effect of the higher dose of calcium gluconate was associated with increased fecal calcium excretion and negative calcium balance. None of the osteoporotic patients showed definite change clinically or on roentgenograms. In view of the evidence available to date, the most likely mechanism for positive calcium balance during high intake is considered to be inhibition of bone resorption. The effect of high calcium intake upon the clinical, structural and chemical course of osteoporosis is as yet unclear. Until this is defined, no statement can be made about the etiologic role of calcium deficiency or the therapeutic usefulness of high calcium intake in osteoporosis.