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Gamma-Glutamyl Transferase (GGT) Test

Published: July 31, 2026Updated: August 10, 2026

A blood test that measures the level of GGT enzyme in your blood to evaluate liver function and detect liver or bile duct disorders. GGT is an enzyme found mainly in the liver, and elevated levels can signal liver damage or a blockage in the bile ducts. Your provider may order this test to check overall liver health, investigate unexplained symptoms, monitor an existing liver condition, or determine whether certain medications or alcohol use are affecting your liver.

Quick summary

{"GGT is an enzyme mainly found in the liver that helps detect liver damage","Elevated GGT levels may indicate liver disease, bile duct problems, or heavy alcohol use","The test is performed on a blood sample taken from a vein in your arm"}

Medically reviewed by WellAlly Editorial TeamLast reviewed August 10, 2026Editorial policy

Key facts at a glance

LOINC
2324-2
Short code
GGT
Synonyms
—
Category
liver
Sample
serum
Container
Serum Separator Tube (SST) or Plain Red Top Tube
Units
U/L
Ref low
9
Ref high
48
Fasting
false
Population
adult
Sex
all
Age range
≥ 18 years
Method
enzymatic
CPT
82947
SNOMED
270000006
Specimen volume
3.5 mL to 5 mL
Stability
Room temperature (20-25°C): 7 days; Refrigerated (2-8°C): 7 days; Frozen (-20°C or below): 30 days. Avoid repeated freeze-thaw cycles.
Hemolysis max
50
Lipemia max
300
Icterus max
20
TAT
1–4 hours

What is a GGT test?

The Gamma-Glutamyl Transferase (GGT) test measures the amount of the GGT enzyme in your blood. GGT is an enzyme primarily found in the liver, but it is also present in the kidneys, pancreas, and other organs. When liver cells are damaged or the bile ducts are blocked, GGT can leak into the bloodstream, causing elevated levels.

Why is this test performed?

Your healthcare provider may order a GGT test to: evaluate liver function, diagnose liver disease or damage, distinguish between liver and bone diseases (when used with other tests like alkaline phosphatase), monitor the progression or treatment of liver disease, or check for bile duct obstruction.

How is the test done?

A healthcare professional will draw a small blood sample from a vein in your arm using a needle. The blood is collected into a tube and sent to a laboratory for analysis. You do not need to fast before this test, but you should inform your doctor about any medications or supplements you are taking, as some can affect the results.

Reference range

Adult male: 0-55 U/L; Adult female: 0-38 U/L. Reference ranges may vary by laboratory and method. Pediatric reference ranges differ by age and should be interpreted using age-specific ranges.U/L

Specimen: serum

Patient should abstain from alcohol for at least 24 hours before sample collection. No fasting required. Inform laboratory of current medications including anticonvulsants, barbiturates, and hepatotoxic drugs that may affect results.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings2

Short name

GGT

Part of panels

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Frequently asked questions

Do I need to fast before a GGT test?
Generally, fasting is not required for a GGT test. However, it is best to follow your healthcare provider's specific instructions. Avoid alcohol for at least 24 hours before the test, as it can significantly affect GGT levels.
What can cause high GGT levels besides liver disease?
Several factors can elevate GGT including heavy alcohol consumption, certain medications (such as some anticonvulsants, antidepressants, and cholesterol-lowering drugs), smoking, obesity, and conditions like diabetes or heart failure. Your doctor will consider these factors when interpreting your results.
Is a low GGT level a concern?
Low GGT levels are usually not concerning and are rarely a problem. GGT levels naturally vary, and low values typically indicate normal liver function. In some cases, low GGT may be associated with certain conditions, but this is uncommon.
How long does it take to get GGT results?
Results are usually available within 1-2 days, though it may take longer depending on the laboratory. Your healthcare provider will contact you with the results or discuss them at your follow-up appointment.
  1. 1
    MedlinePlus - GGT TestSource
  2. 2
    Mayo Clinic - GGT TestSource
  3. 3
    National Institute of Diabetes and Digestive and Kidney Diseases - Liver Blood TestsSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

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 10, 2026. · Read our editorial policy