By calculating the concentration of the enzyme Gamma-glutamyl transpeptidase (GGTP) in your blood, the GGTP test evaluates the condition of your liver. In conjunction with other liver tests like ALT, ASP, ALP, and bilirubin, it is used to diagnose liver illness or bile duct obstructions. The majority of these tests are part of a liver panel, a collection of tests done to look for liver impairment. The typical indications for such a test are drunkenness, jaundice, pancreatitis, any malignancies, or cirrhosis.