GGT test: what the result means

Gamma-glutamyl transferase (GGT) is an enzyme found mostly in the liver, and also in the bile ducts, kidneys and pancreas. It takes part in the metabolism of amino acids and proteins. When liver cells or the bile ducts are damaged, GGT gets into the blood and its level rises. The GGT test is often done together with other liver markers — ALT, AST and alkaline phosphatase — because it helps tell whether a raised alkaline phosphatase is linked to a liver or to a bone disorder: GGT stays normal when the cause is bone. GGT is also used to detect obstruction of the bile ducts (cholestasis) and as an additional marker that helps assess alcohol use, because regular drinking raises GGT. The test needs a venous blood sample.

• When liver disease is suspected — hepatitis, fatty liver disease or cirrhosis
• When other liver tests (especially alkaline phosphatase) are raised and it needs to be established whether the cause is in the liver or in the bones
• When there is tiredness, weakness, a yellow tinge to the skin or the whites of the eyes (jaundice), loss of appetite, abdominal pain or swelling, nausea, vomiting or itching
• When obstruction of the bile ducts is suspected
• When assessing alcohol use or following how it changes over time
• When monitoring the liver while taking medicines that are toxic to the liver

A raised GGT indicates possible damage to the liver or the bile ducts. The most common causes are alcohol use, impaired bile flow, hepatitis or liver cirrhosis. GGT can also rise because of heart failure, pancreatic disease, lung disease or medicines that are toxic to the liver. It is assessed together with the other liver markers.

• Alcohol use
• Impaired bile flow (cholestasis)
• Inflammation of the liver (hepatitis)
• Liver cirrhosis (scarring)
• Impaired blood supply to the liver or damage to liver tissue
• A liver tumour or cancer
• Diabetes mellitus
• Heart failure
• Pancreatic disease
• Lung disease
• Taking medicines that are toxic to the liver

Symptoms that may go with a raised GGT

• Tiredness, weakness
• Jaundice — yellowing of the skin or of the whites of the eyes
• Loss of appetite
• Abdominal pain or swelling
• Nausea and vomiting
• Intense itching

• Other liver markers (ALT, AST, alkaline phosphatase, bilirubin) — they help establish the cause
• An assessment of alcohol use
• The medicines and supplements taken that can raise GGT
• Imaging of the bile ducts, if cholestasis is suspected
• When to repeat the test so that the change over time can be seen

A low or normal GGT

A low or normal GGT usually does not indicate liver disease — according to MedlinePlus, liver disease is then unlikely. The GGT test is meant to detect damage to the liver or the bile ducts, so a lower value in itself does not give a doctor much cause for concern; it is a rise that carries more weight. Some medicines can temporarily lower the GGT result.

• This is regarded as a normal, healthy result that does not indicate a liver disorder
• Some hormonal contraceptives or lipid-lowering medicines can lower the GGT result — it is worth telling your doctor about the medicines you take

If there are symptoms (tiredness, abdominal pain), discuss with your doctor other possible causes that are not related to the liver.

GGT and alkaline phosphatase

Alkaline phosphatase rises with both liver and bone disorders. If GGT is raised at the same time, that indicates the cause is most likely in the liver; if GGT is normal, the cause is more often related to the bones. This is one reason the two are often ordered together.

At the Medicina practica laboratory a GGT test costs from €6 (September 2026 pricing). The price may differ at other laboratories; a family doctor can also order the test free of charge when there are indications for it.