Effect of ethanol on biliary unconjugated bilirubin and its implication in pigment gallstone pathogenesis in humans

Though some epidemiological investigations support the association between pigment gallstone formation and chronic alcoholism with cirrhosis, little attention has been paid to the influence of alcohol itself on biliary bilirubin secretion, so that the pathogenesis of pigment cholelithiasis in alcoholics is hitherto unknown. On different days we intravenously administered ethanol (0.7 g/kg body weight), diluted with 500 ml of saline, or saline alone to 6 non-obese patients with an indwelling T tube and reestablished enterohepatic bile circulation. At the time of the investigation bile cultures were negative for aerobic and anaerobic bacteria. Ethanol significantly increased biliary unconjugated bilirubin in respect to control values. The phenomenon reached a maximum 2 h after alcohol infusion when the value of unconjugated bilirubin averaged 2.37 +/- 0.30% of total bilirubin in contrast to 0.65 +/- 0.14% in control conditions (p less than 0.01), and subsided 6 h after the end of ethanol infusion. Since increased amounts of biliary unconjugated bilirubin predispose to pigment stone formation, it can be speculated that alcohol contributes to pigment cholelithiasis pathogenesis by enhancing the biliary concentrations of this form of pigment.