Plasma 1,25 hydroxycholecalciferol concentrations and net intestinal calcium, phosphate and magnesium absorption in man.

We evaluated the relationship between plasma concentrations of the renal hormone (I,25(OH)2 vitamin D and net intestinal CA,PO4 and Mg absorption in healthy volunteers eating similar diets. Net intestinal CA absorption was positively correlated to plasma I,25(OH)2D concentrations. By contrast, there was no significant correlation between PO4 and Mg absorption and plasma I,25(OH)2D concentrations. We conclude that net intestinal Ca absorption is critically dependent upon the availability of renal homone, while other factors must play a dominant role in regulating net intestinal PO4 and MG absorption.