25-Hydroxylation of vitamin D in primary biliary cirrhosis.

The ability to 25-hydroxylate vitamin D was investigated in thirty-nine patients with symptomatic primary biliary cirrhosis (P.B.C.). In seven previously untreated patients serum-25-hydroxy-vitamin-D (25-OHD) concentration increased after regular monthly injections of vitamin D. After a single injection of vitamin D in eight P.B.C. patients serum-25-OHD did not change significantly over 12 days; in contrast there were significant increases in eight normal subjects and in seven patients with nutritional osteomalacia. Twenty-three of twenty-five P.B.C. patients on regular vitamin-D therapy had normal serum-25-OHD values. These results indicate that serum-25-OHD concentrations become normal in P.B.C. if adequate amounts of vitamin D are presented to the liver as substrate.