title: [Vitamin D metabolism, regulation, function].
abstract: In a review of the literature metabolism, regulation and function of vitamin D and its active metabolites is discussed. Vitamin D is absorbed from the gut and produced in the skin. 25-hydroxylation takes place in the liver, producing 25-hydroxy-vitamin-D. This metabolite is transferred and hydroxylated in the kidney. The most potent cholecalciferol is 1,25-dihydroxy-vitamin-D. This hydroxylation process is regulated by the need of phosphorus and calcium and by calcicotropic hormones, e. g. parathyroid-hormone. The active cholecalciferols regulate intestinal, renal and osseous handling of calcium and phosphorus by binding to a specific receptor protein. Thus, the control of serum calcium and -phosphate homeostasis by cholecalciferols guarantees adequate supply of these substances for mineralisation. Accordingly, perinatal period and puberty is associated with a marked increase in active vitamin D metabolites.
mesh_terms: D001842:Bone and Bones / Q000378:metabolism; D002117:Calcitriol / Q000097:blood; D002118:Calcium / Q000097:blood; D002648:Child; D002762:Cholecalciferol / Q000378:metabolism; D006801:Humans; D007408:Intestinal Absorption; D007668:Kidney / Q000378:metabolism; D010281:Parathyroid Hormone / Q000097:blood; D010710:Phosphates / Q000097:blood; D012279:Rickets / Q000378:metabolism*; D014807:Vitamin D / Q000378:metabolism*; D014808:Vitamin D Deficiency / Q000378:metabolism
chemical_list: D010281:Parathyroid Hormone; D010710:Phosphates; D014807:Vitamin D; D002762:Cholecalciferol; D002117:Calcitriol; D002118:Calcium
vernacular_title: Vitamin-D-Metabolismus, Reguation, Funktion.