γ-glutamyl transferase (GGT)
Why this test?
- To confirm diseases of the liver and biliary tract, especially when biliary obstruction is suspected due to stones in the bile ducts or tumors of the pancreas.
- To monitor the effectiveness of treatment of alcoholism or alcoholic hepatitis. For the diagnosis of diseases affecting the biliary tract - primary biliary cirrhosis and primary sclerosing cholangitis.
- To determine what is causing the increase in alkaline phosphatase activity - liver disease or bone pathology. To monitor the condition of patients with diseases in which GGT is elevated, or to evaluate the effectiveness of their treatment.
In what cases is it prescribed?
- When performing standard diagnostic panels that can be used during routine medical examinations, when preparing for surgical intervention. When performing «liver tests», which are used to assess liver function.
- With complaints of weakness, fatigue, loss of appetite, nausea, vomiting, abdominal pain (especially in the right hypochondrium), jaundice, darkening of urine or lightening of feces, itching of the skin. When alcohol abuse is suspected or when monitoring patients undergoing treatment for alcoholism or alcoholic hepatitis.
Gamma-glutamyltranspeptidase is an enzyme that is located in the cells of the liver and biliary tract and is a catalyst for certain biochemical reactions.
It is not contained in the bloodstream, only in the cells, when their contents are destroyed, they enter the blood. Normally, parts of the cells are renewed, so a certain activity of GHT is detected in the blood. If many cells die, its activity can increase quite significantly. The HGT test is the most sensitive test for bile stagnation - cholestasis.
The activity of GHT increases earlier than the activity of alkaline phosphatase when the outflow of bile is obstructed, for example, with stones in the bile ducts. However, this increase is not specific, as it occurs in most acute diseases of the liver and bile ducts, for example, in acute viral hepatitis or cancer, and usually such a result is not very informative in establishing a specific disease or condition that caused liver damage.
Unlike other liver enzymes, the production of HGT is «triggered» by alcohol, so its activity can be increased in people who abuse it, even in the absence of liver disease. In addition, the production of HGT is stimulated by some drugs, including phenobarbital and paracetamol, so on the background of their intake, an increase in HGT can be expected without liver damage. GHT is also found in the kidneys, spleen, pancreas, brain, prostate, and its increased activity is not specific only for liver disorders.