Gamma-Glutamyl Transpeptidase (GGT) is also known as Gamma-Glutamyl Transferase. It is an enzyme found in the liver, gallbladder, pancreas, and kidneys. It is also found in your blood and other bodily fluids. The Gamma-Glutamyl Transpeptidase (GGT) test measures the amount of Gamma-Glutamyl Transpeptidase enzyme present in your blood. GGT works as a transport molecule that helps to move molecules around the body. It plays a major role in aiding the liver in digesting drugs and other toxins. High levels of GGT in the blood indicate liver damage.