hydroxy Vitamin D3

25-hydroxy Vitamin D3 HIGH D3 Cholecalciferol is an inactivated form of vitamin D3 that has undergone various levels of hydroxylation to form an active vitamin D3 analogue. 1α -hydroxyvitamin D3 (α -calcitol) is a synthetic analogue metabolized to 1, 25-dihydroxycholecalciferol (the bioactive form of vitamin D3). Other analogues of cholecalciferol can be produced by different hydroxylation. 25-dihydroxycholecalciferol is the main circulating form of vitamin D3 and is the physiological precursor of 1α, 25-dihydroxycholecalciferol. This transformation is catalyzed by the 25-hydroxyvitamin D3 1-α -hydroxylase (VD3 1A hydroxylase), also known as cytochrome P450 27B1 (CYP27B1).