Alanine Aminotransferase (ALT)
Alanine aminotransferase (ALT): An enzyme that is normally present in liver and heart cells. ALT is released into blood when one or both of these organs are damaged. Blood ALT levels are thus elevated with liver damage (for example, from viral hepatitis) or with an insult to the heart (for example, from a heart attack). Some medications can also raise ALT levels. ALT is also called serum glutamic pyruvic transaminase (SGPT).