Impaired release of vitamin A from liver in primary biliary cirrhosis

In 44 patients with primary biliary cirrhosis serum levels of vitamin A, retinol-binding protein and transthyretin (prealbumin) were found to be significantly lower than in 25 sex- and age-matched controls. Liver biopsies were available for chemical analyses in 28 of the patients. Their mean liver vitamin A concentration (2.8 +/- 2.0 mumoles per gm wet weight) did not differ significantly from that in 22 cases of sudden death which served as controls (2.0 +/- 1.5 mumoles per gm wet weight). Immunohistochemical investigation showed a normal distribution of serum retinol-binding protein in the patients' livers, whereas the staining pattern of cellular retinol-binding protein, believed to be involved in the intrahepatic transport of vitamin A, was abnormal. Thus, the number size and cellular retinol-binding protein staining intensity of fat-storing (Ito) cells were clearly higher in the patients as compared with controls. The results suggest that the low serum vitamin A levels in primary biliary cirrhosis are not a consequence of vitamin A deficiency but instead reflect a defective mobilization of vitamin A from the liver.