<prompt> Active form of vitamin Li isCholecalciferol24, 25 OH2 vit-D1,25OH 2 vit-D25-OH vit-D  <response>: 1,25011 2 vit-D Ref: Harper 26e, p 484-485; Harrison 16e, p 2246: Chatterjee Shinde Biochemistry 6e, p 151 Synthesis and metabolism of Vitamin D Calcidiol may undergo 24-hydroxylation to yield an inactive metabolite, 24, 25-dihydroxy vit. D mediated by vit. D 24 - hydroxylase. 1, 25 01-12D is the major inducer of vit-D-24 hydroxylase, thus promotes its own inactivation, thereby limiting its biologic effects. 