Serum alanine aminotransferase (ALT) Serum alanine aminotransferase (ALT)

Hepatocyte damage releases the enzyme ALT and high concentrations are therefore indicative of active liver cell damage - whatever the primary cause. It is not a test that measures liver function, as only a small area of liver may be damaged to get significant increases in ALT - usually within 4-5 days. Even very high ALT concentrations can be followed by complete recovery by the liver.

Myocarditis can also result in an increase in ALT, but this is uncommon.