Serum glutamic pyruvic transaminase (SGPT): An enzyme that is normally present in liver and heart cells. SGPT is released into blood when the liver or heart is damaged. The blood SGPT 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 SGPT levels. Also called alanine aminotransferase (ALT).