Gamma-glutamyl transferase GGT
Gamma-glutamyl Transferase (GGT) Test is also known as:
- "gamma-glutamyl transpeptidase,
- GGTP,
- Gamma-GT,
- GTP".
What is Gamma-glutamyl Transferase (GGT) test?
A Gamma-glutamyl Transferase (GGT) test measures the amount of Gamma-glutamyl Transferase in the blood. GGT is an enzyme found in your body tissues and organs, with the highest concentration found in the liver.
This test is used to check liver damage. When the liver is damaged, GGT starts to leak out into the bloodstream. GGT is usually the first liver enzyme to rise in the blood when obstruction or damage to the biliary system occurs. High levels of GGT in the blood indicate liver or biliary system damage.
What is the test used for?
Any damage to the biliary system and liver is checked through the GGT test. This test is non-specific and can't diagnose the specific cause of liver disease alone. So, it's mostly done with other liver function tests like alkaline phosphatase (ALP) which is also a type of liver enzyme. GGT with other liver enzyme tests is used to diagnose liver dysfunction.
Why and when do you need Gamma-glutamyl Transferase (GGT) test?
GGT is most commonly used to;
- Help diagnose liver dysfunction
- Help diagnose if liver damage is due to liver disease or bone marrow disease
- Check the obstruction of bile ducts
- Monitor the alcohol use disorder
If you have any symptoms of liver disease, your doctor might recommend this test along with other liver function tests. The symptoms might include;
- Weakness
- Fatigue
- Jaundice (yellowing of skin and sclera of eyes)
- Loss of appetite
- Weight loss
- Pain in abdomen
- Nausea and vomiting
- Ascites
- Edema
What kind of sample is required for the test?
A blood sample is needed for the GGT test. The laboratory manager takes blood samples by the following methods:
- They wrap a tourniquet around your upper arm and locate the vein
- Upon finding the vein, they carefully insert the needle into it.
- The required blood amount is drawn and collected into the vial.
- Then they will place cotton and bandage above the needle puncture, and you are good to go.
- The blood sample is then sent to run the tests.
Do you need to prepare for the test?
GGT levels usually fall after a meal, so you may be advised not to eat anything for 8hrs before the test. Secondly, different medications and supplements can affect the GGT levels in your blood. Tell your doctors about the medicine you are taking; they might advise you to stop the drugs and take a gap before giving a blood sample.
If you consume alcohol, then test results will vary. Even a tiny amount of alcohol consumption can increase the GGT levels in your blood and give false positives. So, you should avoid taking alcohol at least a day or two before giving the test sample.
Plus, If you have a needle phobia, you should tell the laboratory manager about it. They take preventive measures for it.
Are there any risks to this test?
There is no risk for this test other than that you feel a stinging sensation while the needle is in your vein. After that, there can be pain and bruising, but it disappears soon.
What do the test results mean?
The usual range of GGT tests varies from laboratory to laboratory, but a standard reference range for adults is 5-40 U/L. If results show a higher value of GGT than the average range, you have liver dysfunction or disease. The liver damage may be due to the following conditions:
- Hepatitis
- Alcohol use disorder
- Pancreatitis
- Cirrhosis
- Diabetes
- Congestive heart failure, etc
The results cannot determine which condition is causing the liver to be dysfunctional—the higher the value of GGT, the greater the liver damage.
If results show less or normal GGT value, your liver functions normally.
GGT always proceeds after comparing its results with ALP. ALP helps diagnose bone marrow disorders. Both of the test results are compared, and they may show one of the following:
- High levels of both GGT and ALP show liver damage and not a bone disorder.
- High levels of ALP and low levels of GGT mean it's more likely a bone disorder. Your doctor would correlate the test results with other diagnostic procedures and make the final diagnosis.
Since the average reference value depends upon the laboratory, checking your test result following the given reference value is important.
Related Test:
L-lactate dehydrogenase Test (LDH)
Liver Function Tests (LFTs)
Prothrombin Time (PT)
Bilirubin Test
Frequently ordered together
Alkaline Phosphatase
Aspartate Aminotransferase AST
Bilirubin Direct
Bilirubin Total
Liver Function Test LFT
Alanine Aminotransferase ALT
Ultrasound Liver And Gallbladder
Comprehensive Metabolic Panel CMP without ALT
Hepatic Function Panel
Hepatic Function Panel without Total Proteins
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