Search results
Results from the WOW.Com Content Network
Calcifediol binds in the blood to vitamin D-binding protein (also known as gc-globulin) and is the main circulating vitamin D metabolite. [4] [5] Calcifediol has an elimination half-life of around 15 to 30 days. [4] [9] Calcifediol is further hydroxylated at the 1-alpha-position in the kidneys to form 1,25-(OH) 2 D 3, calcitriol.
Cholecalciferol is a form of vitamin D which is naturally synthesized in skin and functions as a pro-hormone, being converted to calcitriol. This is important for maintaining calcium levels and promoting bone health and development. [4] As a medication, cholecalciferol may be taken as a dietary supplement to prevent or to treat vitamin D ...
These two vitamin D metabolites, collectively referred to as 25-hydroxyvitamin D or 25(OH)D, are measured in serum to assess a person's vitamin D status. Calcifediol is further hydroxylated by the kidneys and certain immune cells to form calcitriol (1,25-dihydroxycholecalciferol; 1,25(OH) 2 D), the biologically active form of vitamin D. [3 ...
Vitamin D oral supplementation and skin synthesis have a different effect on the transport form of vitamin D, plasma calcifediol concentrations. Endogenously synthesized vitamin D 3 travels mainly with vitamin D-binding protein (DBP), which slows hepatic delivery of vitamin D and the availability in the plasma. [9]
Calcitriol is a hormone and the active form of vitamin D, normally made in the kidney. [8] [9] [10] It is also known as 1,25-dihydroxycholecalciferol.It binds to and activates the vitamin D receptor in the nucleus of the cell, which then increases the expression of many genes. [11]
It is able to bind the various forms of vitamin D including ergocalciferol (vitamin D 2) and cholecalciferol (vitamin D 3), the 25-hydroxylated forms (calcifediol), and the active hormonal product, 1,25-dihydroxyvitamin D . The major proportion of vitamin D in blood is bound to this protein.
7-Dehydrocholesterol (7-DHC) is a zoosterol that functions in the serum as a cholesterol precursor, and is photochemically converted to vitamin D 3 in the skin, therefore functioning as provitamin-D 3. The presence of this compound in human skin enables humans to manufacture vitamin D 3 (cholecalciferol).
The conversion of vitamin D, especially cholecalciferol, to 25(OH)D (calcifediol) is one of the key steps in the vitamin D hormonal system. The CYP2R1 enzymatic activity achieving this process was previously thought to be constitutively expressed and stable, so that serum 25(OH)D was a measure of the supply of vitamin D. [9]