Skeletal Regulations (D Gaddy, Section Editor)

Current Osteoporosis Reports

, Volume 10, Issue 2, pp 151-159

Vitamin D and Bone

  • Daniel D. BikleAffiliated withUniversity of California, San FranciscoSan Francisco VA Medical Center Email author 

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Abstract

All cells comprising the skeleton—chondrocytes, osteoblasts, and osteoclasts—contain both the vitamin D receptor and the enzyme CYP27B1 required for producing the active metabolite of vitamin D, 1,25 dihydroxyvitamin D. Direct effects of 25 hydroxyvitamin D and 1,25 dihydroxyvitamin D on these bone cells have been demonstrated. However, the major skeletal manifestations of vitamin D deficiency or mutations in the vitamin D receptor and CYP27B1, namely rickets and osteomalacia, can be corrected by increasing the intestinal absorption of calcium and phosphate, indicating the importance of indirect effects. On the other hand, these dietary manipulations do not reverse defects in osteoblast or osteoclast function that lead to osteopenic bone. This review discusses the relative importance of the direct versus indirect actions of vitamin D on bone, and provides guidelines for the clinical use of vitamin D to prevent/treat bone loss and fractures.

Keywords

Vitamin D Vitamin D receptor CYP27B1 25hydroxyvitamin 1,25 dihydroxyvitamin D 24,25 dihydroxyvitamin D Bone Chondrocytes Osteoblasts Osteoclasts