A vitamin D that is calciol or its hydroxylated metabolites calcidiol and calcitriol. Calciol (also known as vitamin D3) acts as a hormone precursor, being hydroxylated in the liver to calcidiol (25-hydroxyvitamin D3), which is then further hydroxylated in the kidney to give calcitriol (1,25-dihydroxyvitamin D3), the active hormone.
| Member | Definition | Role |
|---|
| 1,23,25-trihydroxyvitamin d3 | A hydroxycalciol that consists of vitamin D3 (calciol) bearing additional hydroxy substituents at positions 1, 23 and 25 (with 1alpha,23S-configuration). An intermediate in the degradation pathway of 1alpha,25-(OH)2D3. | 1alpha,23(S),25-trihydroxyvitamin D3 |
| calcifediol | A hydroxycalciol that is calciol in which the hydrogen at position 25 has been replaced by a hydroxy group. A prehormone resulting from the oxidation of calciol in the liver, it is further hydroxylated in the kidney to give calcitriol, the active form of vitamin D3. | calcidiol |
| calcitriol | A hydroxycalciol that is calcidiol in which the pro-S hydrogen of calcidiol is replaced by a hydroxy group. It is the active form of vitamin D3, produced fom calciol via hydoxylation in the liver to form calcidiol, which is subsequently oxidised in the kidney to give calcitriol. | calcitriol |
| cholecalciferol | A hydroxy seco-steroid that is (5Z,7E)-9,10-secocholesta-5,7,10(19)-triene in which the pro-S hydrogen at position 3 has been replaced by a hydroxy group. It is the inactive form of vitamin D3, being hydroxylated in the liver to calcidiol (25-hydroxyvitamin D3), which is then further hydroxylated in the kidney to give calcitriol (1,25-dihydroxyvitamin D3), the active hormone. | calciol |
| previtamin d(3) | A hydroxy seco-steroid which is an intermediate in the production of vitamin D3 in human skin. | previtamin D3 |