Blood levels of Gammaglutamyltransferase. The enzyme has been found to be a relatively sensitive index of liver damage in clinical studies of alcoholics and heavy drinkers.

Gamma-glutamyltransferase, an enzyme found in the liver which can be measured to detect liver damage.

GGT is an enzyme found mainly in the liver. It is sensitive to changes in liver function. Low levels are normally present in the blood. Elevations can occur in all types of liver disease, and with the consumption of alcohol and some medications. GGT is the most sensitive liver enzyme in detecting bile duct problems. However, it can be elevated even without bile duct problems if someone is overweight or has excess fat in the liver.