52 - Biliary Stone Formation

Abstract

Gallstone disease is a major healthcare concern these days. Gallstones can be classified into three types: cholesterol, black pigment, and brown pigment stones. In Western countries, approximately 75% of gallstones are cholesterol, 20% are black pigment, and 5% are brown pigment stones. Stones can be differentiated by the amount of cholesterol they contain. Cholesterol gallstones contain approximately 85% cholesterol by weight, whereas black pigment stones contain only 1%–2% cholesterol and are made up of unconjugated bilirubin and calcium phosphate; brown pigment stones are composed of calcium bilirubinate and calcium salts of fatty acids. Multiple risk factors have been identified for gallstone development. Major factors that impact on gallstones include age, gender, diet, and genetics. Gallstone incidence increases with age. The vast majority of patients between the ages of 20 and 60 years with gallstones are female, and most of these women develop cholesterol gallstones. Pregnancy and parity are additional risk factors and the influence of estrogens and progesterone on biliary motility and biliary lipid metabolism likely plays a role. Brown pigment stones are associated with conditions that predispose to biliary tract infections, such as parasitic infections, biliary strictures, biliary cysts, and sclerosing cholangitis.