What is the role of aminotransferases in the diagnosis of fatty liver disease?

Updated: Apr 12, 2018
  • Author: Emily Tommolino, MD; Chief Editor: BS Anand, MD  more...
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Abnormal levels of aminotransferases (ie, aspartate aminotransferase [AST] and alanine aminotransferase [ALT]) and bilirubin are found in about one third of hospitalized patients with alcohol-induced steatosis. In such patients, elevated bilirubin levels largely result from an increase in the indirect reacting fraction and may reflect alcohol-associated hemolysis. AST levels are usually higher than ALT measurements. The absolute values of serum AST and ALT are almost always less than 500 IU/L.

An elevated AST or ALT level may be the only abnormality in patients with fatty liver; these levels may be elevated as much as 10-fold. However, AST and ALT levels may be normal in some patients with fatty liver or NASH. In the absence of cirrhosis, an AST-to-ALT ratio greater than 2 suggests alcohol use, whereas a ratio of less than 1 may occur in patients with NASH.

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