GGT blood test
Gamma-glutamyl transferase
In short
A typical adult GGT result is 5 to 36 U/L for women and 8 to 61 U/L for men. A mild rise is very common and often reflects alcohol, extra weight or a medicine. Doctors read it with ALT, AST and ALP rather than alone. Always read your result against the range printed on your own report.
A liver enzyme that rises with alcohol and bile duct problems.
The GGT in blood comes mostly from the liver and its bile ducts, the tubes that drain digestive juice. It rises easily with many liver problems and with regular drinking, so alone it rarely points to one cause. Doctors often use it to tell whether a high ALP comes from the liver or from bone.
Is my GGT high or low?
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Typical range
| For | Range | Unit |
|---|---|---|
| Female | 5–36 | U/L |
| Male | 8–61 | U/L |
Typical ranges for adults. Labs differ a little, so the range printed next to your result is the one to go by.
If your GGT is high
A mild rise is very common and often reflects alcohol, extra weight or a medicine. Doctors read it with ALT, AST and ALP rather than alone.
Common reasons
- Regular drinking, even in moderate amounts
- Extra fat stored in the liver, often with weight gain
- Some medicines, especially some seizure medicines
- Smoking cigarettes
- High blood sugar or diabetes
- Less often: a blocked bile duct, such as from gallstones
- Less often: liver inflammation (hepatitis), liver scarring (cirrhosis) or an inflamed pancreas
If your GGT is low
A low GGT is rarely a concern, and doctors usually don't act on it.
Common reasons
- Normal variation between people
- The later months of pregnancy
- An underactive thyroid
What can throw it off
Regular drinking and some seizure medicines raise GGT, and it can take weeks to settle.
Questions to take to your appointment
- 1Could alcohol, my weight or a medicine explain this?
- 2Do my ALT, AST and ALP point the same way?
- 3Would repeating the test in a few weeks help?
Read together with
Doctors rarely read GGT alone. These usually sit next to it.
Quick answers
What is the GGT blood test?
GGT (Gamma-glutamyl transferase): A liver enzyme that rises with alcohol and bile duct problems. The GGT in blood comes mostly from the liver and its bile ducts, the tubes that drain digestive juice. It rises easily with many liver problems and with regular drinking, so alone it rarely points to one cause. Doctors often use it to tell whether a high ALP comes from the liver or from bone.
What is a normal GGT level?
For most adults, GGT is typically 5 to 36 U/L for women and 8 to 61 U/L for men. Labs differ a little, so the range printed next to your result is the one to go by.
What does a high GGT mean?
A mild rise is very common and often reflects alcohol, extra weight or a medicine. Doctors read it with ALT, AST and ALP rather than alone. Common reasons include regular drinking, even in moderate amounts; extra fat stored in the liver, often with weight gain; some medicines, especially some seizure medicines; and smoking cigarettes. A doctor reads it together with your other results and how you feel.
What does a low GGT mean?
A low GGT is rarely a concern, and doctors usually don't act on it. Common reasons include normal variation between people; the later months of pregnancy; and an underactive thyroid.
What can affect my GGT result?
Regular drinking and some seizure medicines raise GGT, and it can take weeks to settle.
What should I ask my doctor about my GGT?
Questions worth taking to the appointment: Could alcohol, my weight or a medicine explain this? Do my ALT, AST and ALP point the same way? Would repeating the test in a few weeks help?
What this page can’t do
It reads each number on its own.
Doctors read results together — ALT with AST, ferritin with hemoglobin, TSH with free T4. A pattern says more than any single flag.
It doesn't know you.
Your age, your medicines, how you feel and your last result all change what a number means.
It doesn't remember.
Close this page and your results are gone. That's on purpose: nothing was ever sent to us.
We also make Vita: Health Coach, an app for those parts. It reads your whole report with your medicines and history in mind, answers follow-up questions in plain words, and keeps your reports in one place — for you and for the people you look after.
Vita: Health Coach on the App StoreSources
- Mayo Clinic Laboratories — Gamma-Glutamyltransferase (GGT), Serum
- MedlinePlus — GGT test
- Medscape — Gamma glutamyl transferase: reference range and interpretation
Stuck on a word? See the medical words. How we choose our sources. More about Vita Health Coach.