Parathyroid hormone as a trophic hormone for 1,25-dihydroxyvitamin D3, the metabolically active form of vitamin D.

Abstract

Well known to the clinician is the fact that hypoparathyroid patients require large amounts of vitamin D or its close analogue, dihydrotachysterol, for the maintenance of reasonable plasma calcium concentrations. Not so well recognized is the fact that the presence of vitamin D or its metabolites is required for the parathyroid hormone to carry out its well known bone calcium mobilization function in the elevation of serum calcium concentration.1 Finally, hypoparathyroid patients who are resistant to massive amounts of vitamin D have been described.2 From these facts it seems clear that the bone function of both the parathyroid hormone and . . .