Insight into your gamma-GT.
Gamma-GT is an enzyme that points mainly towards the bile ducts and responds sensitively to alcohol and certain medicines. It is often the first liver value to change.
Also known as: GGT, gamma-GT, gamma glutamyl transferase, bile ducts
Personal assessment by our BIG-registered Bloodworks® doctors
By the Bloodworks editorial team
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Background
What is gamma-GT?
Gamma-GT (gamma-glutamyl transferase, abbreviated GGT) is an enzyme found in abundance in the cells that line the bile ducts. If the drainage of bile stagnates, or if the bile ducts become irritated, gamma-GT rises in the blood. It therefore complements the liver tests ALT and AST: those point mainly to irritation of the liver cells themselves, while gamma-GT points more towards bile drainage.
Gamma-GT is sensitive to alcohol and to certain medicines, and is therefore often the first value to respond. A rise does not automatically mean there is damage, but it does indicate that the liver is under load. Because gamma-GT is so sensitive, it is often read together with alkaline phosphatase: if both are raised, that more often points towards the bile ducts; if only gamma-GT is raised, alcohol or medicines often play a role.
In brief
Bile ducts
Points towards the drainage of bile
Sensitive to alcohol
Gamma-GT responds to alcohol and certain medicines
Responds early
Often the first liver value to change
Complements ALT/AST
Together they give a fuller liver picture
This marker is also included in
Testing several values in a single draw takes one blood collection and gives a more complete picture. The choice is yours.
Common reasons to test
When can insight into your Gamma-GT be valuable?
Below are some situations in which measuring Gamma-GT can provide insight.
Part of liver function testing
Gamma-GT is often measured together with ALT and AST. Together these values give a fuller picture of the liver and the bile ducts.
Interpreting a raised alkaline phosphatase
If your alkaline phosphatase is raised, gamma-GT helps determine whether that rise is more likely to come from the liver and bile ducts or from bone.
Insight with alcohol use
Gamma-GT can rise with regular alcohol use and often recovers when you cut down. A test gives factual insight into what this means for your value.
Monitoring with liver-straining medicines
If you take medicines that can put a strain on the liver, checking gamma-GT can be worthwhile. Discuss the frequency with your prescriber.
Following up an earlier liver value
If your gamma-GT or another liver value was previously abnormal, re-testing shows how the value is developing.
With fatigue and liver signals
Fatigue has many possible causes. In combination with other liver signals, gamma-GT can be part of a broader investigation.
What your result means
How do we read your Gamma-GT level?
Gamma-GT is measured in units per litre (U/L). The laboratory states the reference values that apply there alongside your result. Important: alcohol, medication use and fatty liver can influence this value.
A low value
A low gamma-GT generally has no medical significance. Our doctor provides explanation and context with your result.
A normal value
A value within the laboratory's reference values gives a reassuring picture of bile drainage at this moment. It remains a snapshot. The doctor always assesses your value together with your symptoms and your other liver values.
An elevated value
A raised gamma-GT points to load or irritation of the bile ducts. Alcohol and certain medicines are common explanations; fatty liver can also play a role. If your alkaline phosphatase is raised as well, that more often points towards the bile ducts. A single measurement is not a diagnosis. Our doctor explains what your value means and whether re-testing or follow-up via your GP is customary.
How we interpret your result
Our doctors interpret your gamma-GT against the laboratory's reference values and your personal context, such as lifestyle, alcohol use, medication use and any known conditions.
Related tests
Often combined with Gamma-GT.
A single marker gives one perspective. For a broader picture you can combine Gamma-GT with a theme package or related markers.
+ €29 blood draw fee per orderFree from €225
Frequently asked questions
Everything you want to know
What is gamma-GT?
Gamma-GT (gamma-glutamyl transferase, abbreviated GGT) is an enzyme found mainly in the cells around the bile ducts. It is one of the liver values. If gamma-GT rises in the blood, this can fit with load on the liver or irritation of the bile ducts.
Do I need to fast for this test?
No, you do not need to fast for gamma-GT. If you are also measuring glucose or cholesterol at the same time, fasting is customary.
Why is gamma-GT measured together with ALT and AST?
ALT and AST are found mainly in the liver cells and rise with irritation or damage to those cells. Gamma-GT comes mainly from the cells around the bile ducts and points more towards the drainage of bile. They therefore complement each other: together they give a fuller picture of the liver and the bile ducts than each value on its own.
Can alcohol raise my gamma-GT?
Yes, gamma-GT can rise with regular alcohol use. That effect persists for some time after the last drink: with cutting down or stopping, the value usually falls gradually, over weeks to a few months. A rise does not automatically mean there is damage. The doctor takes your alcohol use into account in the interpretation.
Which medicines influence gamma-GT?
Various medicines can raise gamma-GT, for example some anti-epileptics, painkillers and antibiotics. Supplements and herbal preparations can also play a role. Please mention your medication with your result, so the doctor can take it into account. Never stop prescribed medication on your own initiative; always discuss this with your prescriber.
What can a raised gamma-GT mean?
A raised gamma-GT can fit with load on the liver or the bile ducts, for example due to alcohol use, certain medicines, fatty liver or excess weight. A single raised value is not a diagnosis. The doctor always assesses your value together with your other liver values and your context, and where needed discusses the customary next step via your GP.
Is a low gamma-GT a concern?
No. A low gamma-GT generally has no medical significance and requires no follow-up testing.
Can a single elevated value mean a bile duct problem?
No. A single measurement is not a diagnosis. The doctor looks at your gamma-GT together with your other liver values and your context, and advises whether re-testing or follow-up is useful. Gamma-GT is often read together with alkaline phosphatase.
How often should I have gamma-GT measured?
A single measurement is enough for initial insight. With a previously abnormal value or with a lifestyle change you want to follow, re-testing after a few months is customary.
When should I see my GP?
If, alongside an abnormal result, you have symptoms such as jaundice (yellow skin or yellowing of the whites of the eyes), dark urine, pale stools or pain in the upper right side of the abdomen, contact your GP directly. In that case, do not wait for a re-test.
What do I do with my result?
You receive a PDF report with your value and personal explanation. What you do with it, such as discussing it with your GP, remains entirely your choice.
In the Health Guide
Read more about this value
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Ready for insight into your gamma-GT?
You receive your gamma-GT including personal explanation from a doctor, typically within 2 working days. No referral required.
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Combine Gamma-GT with other markers via Bloodworks Select. The blood draw and collection fee is charged once per order, and is waived from €225.
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