The role of biliary calcium in gallstone pathogenesis.

Calcium is an element that is extremely important in the pathogenesis of gallstones. It is present in bile in large quantities since components of bile bind the calcium avidly. Precipitated calcium salts with the calcium sensitive ions, bilirubinate, carbonate and phosphate are major components of pigment gallstones and are present in high concentrations in the centers and rims of cholesterol gallstones. An understanding of the solubility of calcium in bile is thus essential if one is to understand the process that leads to gallstone formation. In addition, calcium also has a very important role in the function of the gallbladder epithelial cell. This manuscript discusses what is known about biliary calcium, the factors that regulate total and free calcium concentrations in bile, the solubility of calcium in both normal and lithogenic bile, and the role calcium plays in epithelial cell function during gallstone formation.