Intestinal absorption of 25-hydroxyvitamin D and osteomalacia in primary biliary cirrhosis.

Bone histology and intestinal absorption of 25-hydroxyvitamin D3 (25-OHD) were investigated in 11 patients with primary biliary cirrhosis (P.B.C.). 4 patients had osteomalacia, and all these had received long-term cholestyramine. Plasma-25-hydroxyvitamin-D (25-OHD) concentrations after an oral dose of 25-OHD3 were significantly lower in the patients with P.B.C. (especially those with osteomalacia) than in normal controls. Serum calcium and urinary calcium excretion were lower, and serum-alkaline-phosphatase higher, in patients with osteomalacia. It is suggested that absorption of 25-OHD undergoing enterohepatic circulation and of dietary vitamin D is reduced in patients with P.B.C. Absorption of 25-OHD is further decreased by cholestyramine and the development of osteomalacia is thus hastened.