Vitamin D in the treatment of osteoporosis revisited.

Interest in vitamin D treatment for osteoporosis has recently been revived because of the focus in various parts of the world on the elderly population, which is predominantly vitamin D deficient, in addition to postmenopausal osteoporosis due to estrogen withdrawal, which has been the central theme of osteoporosis research for many years. Combined use of other agents along with vitamin D has fortified the therapeutic armory against osteoporosis. The recent suggestion of a role of vitamin D receptor polymorphism in the development and progress of osteoporosis, possibly by interfering with its expected action, provoked intense discussions on the role of vitamin D in the pathogenesis and treatment of osteoporosis. Vitamin D receptor polymorphism may explain some of the racial differences in the incidence of osteoporosis and its complications. Responses to vitamin D treatment may also be predicted by vitamin D receptor allelic analysis, though the currently proposed allelic patterns are yet far from being widely accepted. The outlook for vitamin D treatment for osteoporosis may require insight into vitamin D receptor, not only for vitamin D's given form, but also for a possible future form designed to intervene at the genomic level.