Gamma Glutamyl Transferase (GGT)

CPT Code: 82977
Specimen: Serum of Plasma
Volume: 1 mL
Minimum Volume: 0.5 mL
Container: Red-top tube, gel-barrier tube, green-top (heparin) tube, or lavender-top (EDTA) tube
Methodology: Kinetic
Collection:

Separate serum or plasma from cells within 45 minutes of collection.  Clot formation should take place before centrifugation.

Blood collection stubs containing a combination of potassium oxalate and sodium fluoride will decrease GGT activity by 15%.

Reference Range:  

Stability: 

Temperatures Period
Room Temperature 8 Hours
Refrigerated (2-8 ⁰C) 2 Days
Frozen (≤ -20 ⁰C) Longer Storage

          

 

Use: A biliary enzyme that is especially useful in the diagnosis of obstructive jaundice, intrahepatic cholestasis, and pancreatitis.
Clinical Significance: High GGT may be present in hepatoma, seminoma and carcinoma of pancreas.  It is useful in diagnosis of chronic alcoholic liver disease, but some heavy drinkers do not have GT increases.

GT is the test for cholestasis during or immediately following pregnancy. Commonly elevated in cirrhosis and hepatitis. The transaminases, AST and ALT rise higher in acute viral hepatitis; these tests with GT and other parameters are best used together in work-up of liver disease. In ascitic fluid, very high GT is said to suggest hepatoma as opposed to cirrhosis or liver metastases.

Increased in systemic lupus erythematosus. Very high levels are common in primary biliary cirrhosis. High GT is found in infants with biliary atresia. GGT is also increased with hyperthyroidism.

Low GGT may be present in hypothyroidism.   

Causes for Rejection: Gross hemolysis; improper labeling; gross lipemia
Interfering Substances: Hemolysis (hemolysate) of 500 mg/dL (monomer) and above tripped a test report message; therefore the magnitude of the interference could not be determined.

 
Bilirubin (unconjugated) of 60 mg/dL and above tripped a test report message; therefore the magnitude of the interference could not be determined.

Triglycerides as (Intralipid) of 200 mg/dL decreases GGT at 128 U/L by 16%.