Lithogenesis and bile metabolism.

Gallstone disease exacts a considerable financial and social burden worldwide leading to frequent physician visits and hospitalizations. Based on their composition, gallstones are categorized as cholesterol, black pigment, and brown pigment, with each category having a unique structural, epidemiologic, and risk factor profile. Cholesterol crystal formation requires the presence of one or more of the following: (a) cholesterol supersaturation, (b) accelerated nucleation, or (c) gallbladder hypomotility/bile stasis. Some risk factors for cholesterol stones include age, gender, genetics, obesity, rapid weight loss, and ileal disease. Generally, pigment stones are formed by the precipitation of bilirubin in bile, with black stones associated with chronic hemolytic states, cirrhosis, Gilbert syndrome, or cystic fibrosis, and brown stones associated with chronic bacterial or parasitic infections.