Alanine aminotransferase (ALT) - plasma or serum

Last updated: Thursday, 18, March, 2004

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Item Process

5 mL blood in lithium heparin or plain tube.



Reference Interval

Adult: <35 U/L
Neonate: <50 U/L


Detection and monitoring of liver cell damage.


Increased ALT levels are associated with hepatocellular damage.

ALT is more specific for hepatocellular damage than is AST or LD and remains elevated for longer, due to its longer half-life.

The AST/ALT ratio is typically >1 in alcoholic liver disease and <1 in non-alcoholic liver disease.

ALT may be slightly elevated in skeletal muscle disease but the degree of elevation is much less than for AST and CK.


Rochling FA. Clin Cornerstone 2001; 3(6): 1-12.