Optimal Evaluation of the Results of Liver Function Tests

Physicians of all specialties are required to assess abnormal results of liver function tests.Many patients with abnormal results in liver function tests do not have primary liver disease; most of the frequently requested tests are influenced by myriad non-hepatic factors.The most common tests are those for serum levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), and bilirubin.Hepatocellular injury is indicated by abnormally elevated AST and ALT levels compared to the ALP level.Cholestatic injury is indicated by an abnormally elevated ALP level compared to AST and ALT levels.The majority of bilirubin circulates as unconjugated bilirubin, and an elevated conjugated bilirubin level is a marker of hepatocellular or cholestatic injury.Obtaining a detailed medical history, a clinical examination, and optimal interpretation of abnormal results of liver tests can enable the determination of the cause of liver diseases, facilitating their diagnosis and therapy.(Korean J Med 2019;94:89-95)