ALT

Background

• Alanine aminotransferase; more specific to the liver than AST
• Found primarily in hepatocytes

Normal Values

• Normal: 7-56 U/L

Interpretation

• Most specific widely-available marker of hepatocellular injury
• ALT >1000 U/L: acetaminophen toxicity, ischemic hepatitis, acute viral hepatitis, acute biliary obstruction
• Mild elevations (1-3x normal): fatty liver, medications, chronic hepatitis, celiac disease
• Moderate elevations (3-10x normal): acute/chronic hepatitis, autoimmune hepatitis, medications
• ALT may be normal in advanced cirrhosis (insufficient hepatocytes to release enzyme)

See Also

• AST
• Liver function tests
• Hepatitis