Serum or plasma gamma-glutamyl transferase (GGT) activity
This test measures the activity of an enzyme called gamma-glutamyl transferase, which helps break down certain amino acids. It’s often checked to evaluate liver function and detect potential liver damage or disease.
["GGT helps identify liver issues, including alcohol-related damage or bile duct problems."]
Key facts at a glance
- LOINC
- 2325-9
- Short code
- GGT/AST SerPl-cRto
- Synonyms
- GGT/AST SerPl-cRto
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 10
- Ref high
- 40
- Critical range
- — – 500 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 84484
- SNOMED
- 302774002
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
What Does GGT Measure?
GGT is an enzyme found in the liver, bile ducts, and other parts of the body. When the liver is inflamed, damaged, or diseased, GGT levels in the blood can rise. This test is particularly useful for spotting conditions like alcohol-related liver disease, certain cancers, or blockages in the bile ducts.
Why Might You Need This Test?
Your doctor may order a GGT test if you have symptoms like jaundice (yellowing of the skin or eyes), abdominal pain, fatigue, or if you’ve been drinking alcohol heavily. It’s also used during liver function tests or to monitor conditions like hepatitis or cirrhosis.
Common Causes of Elevated GGT Levels
High GGT levels can result from liver problems, such as hepatitis (viral, alcoholic, or autoimmune), fatty liver disease, or cirrhosis. It may also appear in conditions affecting the bile ducts (like cholestasis) or certain medications that strain the liver.
What If My GGT Is High?
If your GGT is elevated, your doctor will likely investigate further with additional tests or imaging to determine the cause. This could include blood tests for liver enzymes, imaging studies (like an MRI or ultrasound), or a review of your medical history and lifestyle.
Reference range
Adult: 10-40 U/LN/A
No special preparation required. Avoid fatty meals before the test if possible.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Elevated GGT levels may indicate liver stress or damage, but they’re not always definitive on their own. They’re often used alongside other tests to guide diagnosis and treatment planning.
Short name
GGT
Frequently asked questions
What are the normal ranges for GGT?
Does diet or alcohol affect GGT levels?
How long does it take to get results?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 17, 2026. · Read our editorial policy