Serum 25-hydroxyvitamin D concentrations in patients receiving chronic corticosteroid therapy.

Serum 25-hydroxyvitamin D (25OHD) concentrations were measured by competitive protein-binding assay in 21 patients who were receiving chronic prednisone therapy and who demonstrated radiologic osteopenia. Results were compared to values obtained in 19 matched non-steroid-treated control subjects. Serum 25OHD values in control and steroid-treated subjects were virtually identical and showed a similar positive correlation with vitamin D intake. To rule out possible assay interference by postulated steroid-induced abnormal vitamin D metabolites, 25OHD was specifically isolated from pooled extracts of control and steroid-treatment patient sera by silicic acid column chromatography. 25OHD levels were again identical in both groups, and there was no evidence of radioassayable abnormal metabolites. It is concluded that the maintenance of normal serum levels of 25OHD is not altered by chronic moderate dose corticosteroid therapy.