Vitamin D metabolism in man. Effect of corticosteroids.

This study evaluated the effects of acute intravenous calcium supplementation on vitamin D metabolism in nine patients maintained on long-term prednisone therapy for chronic obstructive lung disease. Vitamin D turnover studies, employing 1,2-(3)H,4(14)C vitamin D3, and coincident measurement of serum 25-hydroxycholecalciferol (25-OHCC) concentrations demonstration (P less than .05) and half-time (P less than .05) in the prednisone-treated patients when compared with the mean 25-OHCC concentration and half-time found in these patients prior to calcium infusion. However, there was no significant difference in the amounts of 24,25-(OH)2CC) or 1,25-dihydroxycholecalciferol (1,25-(OH)2CC) appearing after calcium infusion. The results of the study showed that the intravenous administration of calcium to corticosteroid-treated patients accelerated the disappearance of 25-OHCC from the plasma of these patients without parallel increases in the production of 1,25-(OH)2CC or 24-25-(OH)2CC.