The evaluation of patients who have abnormal liver test results includes many clinical factors: the chief complaints of the patient, patient age, risk factors for liver disease, personal or family history of liver disease, medications, and physical examination findings. Because of these many factors, designing a standard algorithm for the evaluation of abnormal liver test results is difficult and often inefficient. Nevertheless, with basic information, abnormalities can be evaluated in an efficient, cost-effective manner. Diseases that predominantly affect the biliary system are called cholestatic diseases. They can affect the microscopic ducts (eg, primary biliary cirrhosis) or the large bile ducts (eg, pancreatic cancer causing obstruction of the common bile duct), or both (eg, primary sclerosing cholangitis).