title: Vitamin D actions to regulate calcium and skeletal homeostasis.
abstract: The endocrine action of plasma 1,25-dihydroxyvitamin D plays a key role in the regulation of plasma calcium and phosphate homeostasis with activities on the intestine, kidney and bone. A current, controversial question is whether vitamin D exerts direct actions on bone cells to regulate bone mineral homeostasis. Results from clinical, rodent model and in vitro studies on human bone cells provide an impressive body of data to support this proposal particularly at the level of serum 25-hydroxyvitamin D status. Each of the major bone cell types is capable of metabolising vitamin D to the active metabolite, 1,25-dihydroxyvitamin D. Thus under conditions when bone tissue synthesis of 1,25-dihydroxyvitamin D is optimal, vitamin D activity enhances bone mineral status. Dietary calcium and phosphate intakes are the critical environmental cues together with vitamin D status to determine whether 1,25-dihydroxyvitamin D exerts an anabolic or catabolic action on bone mineral status.
authors.affiliation: School of Pharmacy and Medical Sciences, University of South Australia, and Chemical Pathology Directorate, SA Pathology, Frome Road, Adelaide 5000 SA, Australia.
authors.forename: Paul H
authors.initials: PH
authors.lastname: Anderson
authors.forename: Andrew G
authors.initials: AG
authors.lastname: Turner
authors.forename: Howard A
authors.initials: HA
authors.lastname: Morris
mesh_terms: D015090:25-Hydroxyvitamin D3 1-alpha-Hydroxylase / Q000235:genetics / Q000378:metabolism; D000818:Animals; D001842:Bone and Bones / Q000166:cytology / Q000378:metabolism*; D002113:Calcification, Physiologic; D002118:Calcium / Q000097:blood / Q000378:metabolism*; D004032:Diet; D006706:Homeostasis; D006801:Humans; D010710:Phosphates / Q000378:metabolism; D013250:Steroid Hydroxylases / Q000235:genetics / Q000378:metabolism; D014807:Vitamin D / Q000097:blood / Q000502:physiology*; D065668:Vitamin D3 24-Hydroxylase
chemical_list: D010710:Phosphates; D014807:Vitamin D; D013250:Steroid Hydroxylases; D065668:Vitamin D3 24-Hydroxylase; D015090:25-Hydroxyvitamin D3 1-alpha-Hydroxylase; D002118:Calcium