The gamma GT test is another term for the gamma-glutamyl transpeptidase (GTT) screening. It is an extremely comprehensive test that looks for liver function or potential liver disease. This test measures the blood level of GGT, a liver enzyme that serves a key role as a transport molecule, and helps the liver metabolize substances, such as drugs, alcohol, and toxins. Read on to learn about GGT, why the test is ordered, and what elevated levels may mean.
Why Is the GGT Test Ordered?
Unlike some other routine blood tests, the gamma GT test is ordered because your physician suspects liver disease. It is not part of a complete blood count (CBC) or other batteries of tests that check for overall health. The GGT test is the gold standard to measure the enzyme function in the liver. It is often ordered for those who suffer from alcohol use disorder (AUD), who may have done damage to their liver. However, liver damage can also be caused by poison ingestion, drug abuse, and other diseases. All toxins must filter through the liver, and if there is an overabundance of toxins at a given time or over a period of time, the liver may incur damage.
What Are the Symptoms of Liver Problems?
If your doctor has ordered a GGT test, he or she either suspects liver problems, or you are presenting with symptoms that indicate a liver condition. Some common symptoms of liver problems include:
- Dark urine
- Light-colored feces
- Jaundice (yellowing of the skin and eyes)
- Abdominal pain
- Nausea and/or vomiting
- Lack of appetite
- Itchy skin
It is true that many of these symptoms may be indicative of other problems, such as gastrointestinal upset. Your doctor may want to rule out a liver problem to find the correct diagnosis.
What Are Normal and High Gamma GT Levels?
Normal GGT levels fall between 0 and 30 international units per liter (IU/L), for both children and adults, though these levels may be slightly higher in newborn infants. Levels of GGT can also vary depending on circumstances. If a person with alcohol use disorder has had a drink the night before the test, the test could be wildly elevated. However, a person with AUD who has had even a short period of sobriety may have a normal level. Unless the liver is permanently damaged, as with cirrhosis (scarring of the liver), it is extremely elastic and can “bounce back,” even from high levels of GGT and moderate liver damage. If alcohol is the culprit, however, the person must maintain sobriety in order for the liver to recover. High GGT levels are any level above the 30 international units per liter mark.
What Are Other Causes of High GGT?
Alcohol abuse is most often the cause of high GGT levels, but there can be other reasons. High gamma GT levels may also be caused by hepatitis, liver tumor, cirrhosis of the liver, diabetes, pancreatitis, and nonalcoholic fatty liver disease (NAFLD). If your GGT level is high, your doctor will likely want to order further tests to check your liver.
What Other Tests Check Liver Functioning?
A GGT test is the most comprehensive of the liver function tests. Still, your physician may want to order other tests, or perform more invasive procedures, such as a liver biopsy. Other liver function tests include the alanine transaminase (ALT) test, the aspartate aminotransferase (AST) test, and the alkaline phosphatase (ALP) test. These are all enzyme blood tests.
What Is the Outlook for Liver Disease?
With the exception of cirrhosis, which is irreversible, the outlook for liver disease as it relates to alcoholism or alcohol abuse is fairly positive, provided the patient stops drinking and maintains sobriety. The liver is a versatile organ, and can easily revert back to its original functioning provided it is no longer having to filter high levels of toxins (such as alcohol). Liver disease with respect to alcohol for a patient who is unable to stop drinking has a poor prognosis. Many cases of liver disease will progress to cirrhosis, which is often terminal.