GGT (Gamma-Glutamyl Transferase)
Definition
GGT is an enzyme found mainly in the liver. When the liver or bile ducts are damaged, GGT leaks into the blood.
Purpose
- Diagnosis of liver diseases
- Distinguishing liver disease from bone disease (see below)
- Detection of bile duct obstructions
- Screening for or monitoring alcohol use disorder (AUD). Alcohol consumption raises GGT levels.
Results
- High, liver damage due to hepatitis, cirrhosis, alcohol use disorder, pancreatitis, diabetes or heart failure
- Normal/low, suggests no liver disease
When interpreted together with ALP, it gains discriminating power:
| GGT | ALP | Interpretation |
|---|---|---|
| High | High | Problem of liver origin |
| Normal | High | Problem of bone origin |
This is a very useful distinction for finding the cause of a high ALP, since ALP is present in both liver and bone and cannot be interpreted on its own.
Normal Values
Laboratory specific.
Risks and Limitations
The GGT test cannot diagnose the specific cause of liver disease; it only shows that damage is present.