title: Effect of the administration of 1,25-dihydroxyvitamin D3 on serum levels of 25-hydroxyvitamin D in postmenopausal osteoporosis.
abstract: Serum concentrations of 25-hydroxyvitamin D were measured in a group of women with symptomatic postmenopausal osteoporosis, before and after long-term treatment with physiological doses of 1,25-dihydroxyvitamin D3. A competitive protein binding assay was used, which included a chromatographic step. The treatment resulted in a significant decrease in serum 25-hydroxyvitamin D levels that were higher than normal in basal conditions, the mean values before and after therapy being 27.7 ng/ml (+/- 17.1 SD) and 19.7 ng/ml (+/- 12.7), respectively. These findings seem to confirm the hypothesis that an inadequate product-inhibition of liver 25-hydroxylase is responsible for the increased basal levels of 25-hydroxyvitamin D found in postmenopausal osteoporosis.
mesh_terms: D015652:25-Hydroxyvitamin D 2; D000368:Aged; D002117:Calcitriol / Q000627:therapeutic use*; D004872:Ergocalciferols / Q000031:analogs & derivatives* / Q000097:blood; D005260:Female; D006801:Humans; D007408:Intestinal Absorption / Q000187:drug effects; D008593:Menopause; D008875:Middle Aged; D010024:Osteoporosis / Q000097:blood* / Q000188:drug therapy
chemical_list: D004872:Ergocalciferols; D015652:25-Hydroxyvitamin D 2; D002117:Calcitriol