This test is often done in conjunction with other tests that measure liver enzymes. The liver is crucial for producing proteins in the body and filtering out poisons. It also makes bile, a substance that helps the body process fats. Your doctor may order the GGT if your liver is suspected to be damaged. Often, this stems from heavy use of alcohol or other toxic substances, like drugs or poisons.
Symptoms of liver problems include:
- decreased appetite
- vomiting or nausea
- lack of energy
- abdominal pain
- jaundice (a yellowing of the skin)
- unusually dark urine or light-coloured feces
- itchy skin
If you have finished an alcohol rehab program and are trying to abstain from alcohol, your doctor might order this test to check compliance with your treatment program. The test can also monitor levels for people who have been treated for alcoholic hepatitis.Your doctor may instruct you to fast for eight hours before the test and to stop taking certain drugs. Phenobarbital, phenytoin, and alcohol can raise your GGT level. Birth control pills and clofibrate may decrease your GGT level. If you drink even a small amount of alcohol within 24 hours of the test, it can affect your results. The GGT test is somewhat equivocal, because while it can diagnose liver damage, it can’t determine the cause. If your GGT is elevated, you’ll probably have to undergo more tests.
Some of the conditions that result in increased GGT include:
- overuse of alcohol
- lack of blood flow to the liver
- liver tumors
- cirrhosis (scarred liver)
- overuse of drugs or other toxins
- heart failure
GGT is often measured relative to another enzyme, alkaline phosphatase (ALP). If both are elevated, doctors will suspect problems with the liver or the bile ducts. If GGT is normal and ALP is elevated, this could indicate bone disease. Therefore, the GGT test may be used to rule out certain problems when making a diagnosis.