When a high level of a toxin like alcohol or poison is in the body, the cells respond quickly with detoxification enzymes (1p23). One such enzyme is glutamyl transferase (GGT) (1p23) that is largely present in hepatocytes. The enzyme plays a role in transferring amino acids across the cell membrane and the biosynthesis of the antioxidant glutathione (2).
A simple blood test called a gamma-glutamyl transpeptidase (GGTP) can indicate if levels of GGT are greater than normal (2). The test is performed by drawing blood from the elbow orback of the hand (2).
An increase in GGT levels could be caused by alcohol intake, heart failure, cholestatis, cirrhosis, hepatitis, liver ischemia, liver necrosis, liver tumor or a drug/poison toxic to the liver (2). A decrease in levels could be caused by clofibrte or birth control pills (2).
Because it is unclear what elevated GGT levels may indicate, physicians will often also include other tests such as one for the enzyme ALP (3). If only GGT is elevated, then the cause may be alcohol abuse, but if GGT and ALP are elevated, then the diagnosis could be liver disease (3). In some people ALP only may be elevated, which could indicate bone disease (3).
1. Nowak TJ, Hanfod AG. Pathophysiology: Concepts and applications for health care professionals, 3rd ed. 2004. New York, McGraw-Hill.
2. MedlinePlus. Gamma-glutamyl transpeptidase. Available at: http://www.nlm.nih.gov/medlineplus/ency/article/003458.htm.
3. Lab Tests Online. GGT. Available at: http://www.labtestsonline.org/understanding/analytes/ggt/test.html.