Increased biliary calcium in cholesterol gallstone formation.

The hypothesis that biliary calcium levels increase during cholesterol gallstone formation was tested in a prairie dog gallstone model. In addition to the previously documented changes in biliary lipid composition, animals with gallstones had a significant increase in gallbladder bile concentrations of total and ionized calcium compared with control animals. The observation that hepatic bile levels of calcium remained unchanged in the cholesterol-fed animals suggests that the increase in gallbladder bile calcium is due to a gallbladder-related phenomenon, rather than an alteration in hepatic metabolism. We proposed that this increase in biliary calcium levels results from an increase in gallbladder absorption. Increased biliary calcium levels may be an important, previously unrecognized, factor in the pathogenesis of cholesterol gallstones.