The level of circula ng 1,25- dihydroxycholecalciferol is significantly reduced in patients with chronic liver disease because: (A) The liver can no longer efficiently conve 25-hydroxycholecalciferol to 1,25-dihydroxycholecalciferol, (B) The liver can no longer efficiently conve vitamin D to cholecalciferol, (C) The liver can no longer efficiently conve vitamin D to 25- hydroxycholecalciferol, (D) The liver can no longer efficiently conve cholecalciferol to 1,25-dihydroxycholecalciferol
Answer is C. A healthy liver conves vitamin D (cholecalciferol) to form 25-hydroxycholecalciferol, but a diseased liver has a reduced capacity to do so. The kidney, not the liver, is responsible for the conversion of 25 hydroxycholecalciferol to 1,25-dihydroxycholecalciferol. Vitamin D, not 1,25-hydroxycholecalciferol, is absorbed by the small intestine.