title: Vitamin D and osteoporosis.
abstract: In elderly people with marginal exposure to the sunlight, males showed higher serum 25-hydroxycalciferol than females, whereas in those with ample or poor sunlight exposure, serum 25-hydroxycalciferol was higher or very low, respectively, exhibiting no sex difference in the vitamin D metabolite levels. The male predominance in serum 25-hydroxycalciferol levels seen among some aged population would be explained, at least in part, by the result of animal experiment suggesting the stimulatory effect of testosterone on vitamin D biosynthesis induced by ultaviolet irradiation. Testosterone was, furthermore, shown to have hypocalcemic action, probably through suppression of bone resortopton in vitamin D depleted but not in replete rats. Clinical implication of these two-fold effects of testosterone observed in rats was discussed in relevance to male predominance in serum 25-hydroxycalciferol level and bone mineral content in the aged population.
mesh_terms: D000368:Aged; D000818:Animals; D001842:Bone and Bones / Q000032:analysis; D005260:Female; D006801:Humans; D006887:Hydroxycholecalciferols / Q000097:blood*; D008297:Male; D008875:Middle Aged; D008903:Minerals / Q000032:analysis; D010024:Osteoporosis / Q000378:metabolism / Q000503:physiopathology*; D051381:Rats; D012737:Sex Factors; D013472:Sunlight; D013739:Testosterone / Q000494:pharmacology; D014807:Vitamin D / Q000096:biosynthesis / Q000378:metabolism*
chemical_list: D006887:Hydroxycholecalciferols; D008903:Minerals; D014807:Vitamin D; D013739:Testosterone