| 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 |
| 1,25-dihydroxy-24-oxo-vitamin d3 | | (1S)-1,25-dihydroxy-24-oxocalciol |
| 1,25-dihydroxyergocalciferol | A hydroxycalciol that is vitamin D2 bearing additional hydroxy substituents at positions 1alpha and 25. | 1alpha,25-dihydroxyvitamin D2 |
| 25-hydroxy-24-oxocholecalciferol | | 25-hydroxy-24-oxocalciol |
| 25-hydroxyvitamin d 2 | A hydroxycalciol that is vitamin D2 in which the hydrogen at position 25 has been replaced by a hydroxy group. | 25-hydroxyvitamin D2 |
| calcifediol | A hydroxycalciol that is calciol in which the hydrogen at position 25 has been replaced by a hydroxy group.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 |
| calcitroic acid | A hydroxycalciol that is calcidiol in which the pro-S hydrogen of calcidiol is replaced by a hydroxy group and the C-23/C-27 unit is replaced by a carboxy group. | calcitroic acid |