Gamma Glutamyl Transferase (GGT)

The Gamma Glutamyl Transferase (GGT) test measures the level of GGT, an enzyme found in many organs, especially the liver. GGT plays a role in the transport of amino acids and the metabolism of glutathione. Elevated GGT levels often indicate liver damage or bile duct problems.

1. What Is GGT?

• GGT is an enzyme concentrated in the liver, bile ducts, and kidneys.

• It is involved in the metabolism of glutathione and helps transport amino acids across cell membranes.

• GGT is commonly used as a marker for liver and bile duct function, particularly to detect bile obstruction or alcohol-related liver disease.

2. Why Is the GGT Test Performed?

This test is used to:

• Detect liver or bile duct damage.

• Determine the cause of elevated alkaline phosphatase (ALP) levels.

• Monitor chronic alcohol use and related liver damage.

• Assess exposure to liver-toxic substances or medications.

3. GGT Reference Range

• Men: 8 – 61 U/L

• Women: 5 – 36 U/L

• Reference ranges may vary depending on the laboratory and patient factors such as age or gender.

4. How to Interpret GGT Results

🔹 Elevated GGT:

• May suggest liver disease, bile duct obstruction, or alcohol abuse.

• Can be caused by fatty liver disease, hepatitis, cirrhosis, or drug-induced liver injury.

• When ALP is also elevated, high GGT confirms a hepatobiliary source.

🔹 Normal GGT:

• Typically rules out significant bile duct or liver damage.

• Helps differentiate bone-related elevations in ALP (e.g., GGT normal, ALP elevated suggests bone source).

5. What Can Affect GGT Levels?

• Chronic alcohol use (even without other symptoms)

• Medications (e.g., phenytoin, barbiturates, NSAIDs, statins)

• Liver diseases (e.g., hepatitis, cirrhosis, fatty liver)

• Smoking and obesity

• Age and gender (GGT may naturally increase with age)

6. How Is the Test Performed?

• A blood sample is drawn from a vein.

• Fasting may be recommended before testing for accurate interpretation.

7. When to See a Doctor

🚨 Contact your healthcare provider if you:

• Have abnormal GGT or ALP levels on blood work.

• Show signs of liver or gallbladder disease (e.g., jaundice, fatigue, dark urine, abdominal pain).

• Are taking medications that affect the liver or drink alcohol regularly.

🔹 Key Takeaways

✅ GGT is a sensitive marker for liver and bile duct function.

✅ Elevated levels can indicate liver disease, bile obstruction, or alcohol use.

✅ GGT is helpful in determining the cause of elevated liver enzymes, especially ALP.