Posted by JK from IP 129.252.69.45 on July 17, 2008 at 15:17:32:
In Reply to: Re: Let's do Pathology cases-9 posted by Dr D on July 17, 2008 at 13:21:17:
Right!!
A. The main source of vitamin D is the conversion of 7-dehydrocholesterol to cholecalciferol by sunlight in the skin. This reaction forms previtamin D3 (cholecalciferol), which in the liver is converted to 25-hydroxy-D3 (calcifediol) by a cytochrome P-450 mixed-function oxidase. Calcifediol is converted in the kidney to 1,25-dihydroxy vitamin D3 (calcitriol, the most potent vitamin D metabolite) by a renal tubular mitochondrial hydroxylase: 1-alpha-hydroxylase.