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Approach to the patient with abnormal liver biochemical and function tests

Lawrence S Friedman, MD
Section Editor
Sanjiv Chopra, MD, MACP
Deputy Editor
Shilpa Grover, MD, MPH, AGAF


Abnormal liver biochemical and function tests are frequently detected in asymptomatic patients since many screening blood test panels routinely include them [1]. A population-based survey in the United States conducted between 1999 and 2002 estimated that an abnormal alanine aminotransferase (ALT) was present in 8.9 percent of respondents. Although the term "liver function tests" (LFTs) is used commonly, it is imprecise and potentially misleading since many of the tests reflecting the health of the liver are not direct measures of its function. Furthermore, the commonly used liver biochemical tests may be abnormal even in patients with a healthy liver.

This topic review will provide an overview on the evaluation of patients with abnormal liver biochemical and function tests. Our approach is largely consistent with the 2017 American College of Gastroenterology clinical guidelines on evaluation of abnormal liver biochemistries [2]. Detailed discussions of the individual tests are presented separately. (See "Liver biochemical tests that detect injury to hepatocytes" and "Enzymatic measures of cholestasis (eg, alkaline phosphatase, 5'-nucleotidase, gamma-glutamyl transpeptidase)" and "Classification and causes of jaundice or asymptomatic hyperbilirubinemia" and "Tests of the liver's biosynthetic capacity (eg, albumin, coagulation factors, prothrombin time)".)


Alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase and bilirubin are biochemical markers of liver injury. Albumin, bilirubin, and prothrombin time are markers of hepatocellular function.

Elevations of liver enzymes often reflect damage to the liver or biliary obstruction, whereas an abnormal serum albumin or prothrombin time may be seen in the setting of impaired hepatic synthetic function. The serum bilirubin in part measures the liver's ability to detoxify metabolites and transport organic anions into bile.

Liver enzymes — Liver enzymes that are commonly measured in the serum include:

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Literature review current through: Nov 2017. | This topic last updated: Nov 16, 2017.
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