Gamma Glutamyl Transferase

Test Code

GGT

Alias/See Also

Gamma GT, GGT

Preferred Specimen

1.0 mL plasma (0.5 mL minimum)

Transport Container

PST (light green top). Red top and SST also acceptable

Specimen Stability

Room temperature: 7 days, Refrigerated: 7 days, Frozen: 6 months

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)

Grossly hemolyzed specimens are unacceptable.

Reference Range

Age	Female	Male
Adult (>19 years):	5-55 U/L	5-85 U/L
Pediatric:
0 – 7 days	18-148	25-168
8 days – 30 days	16-140	23-174
1 – 3 months	16-140	16-147
4 – 6 months	13-123	5-93
7 – 11 months	8-59	8-38
1 – 3 years	2-15	2-15
4 – 6 years	5-17	5-17
7 – 9 years	9-20	9-20
10 – 11 years	12-23	12-25
12 – 13 years	10-20	12-39
14 – 15 years	10-22	8-29
16 – 19 years	6-23	6-30

Clinical Significance

"Gamma-glutamyl transferase is markedly increased in lesions that cause intrahepatic or extrahepatic obstruction of bile ducts, including parenchymatous liver diseases with a major cholestatic component (e.g., cholestatic hepatitis). Lesser elevations of gamma-GT are seen in other liver diseases, and in infectious mononucleosis, hyperthyroidism, myotonic dystrophy, and after renal allograft. Drugs causing hepatocellular damage and cholestasis may also cause gamma-GT elevation.
Gamma-GT is a very sensitive test for liver damage, and unexpected, unexplained mild elevations are common. Alcohol consumption is a common culprit.
Decreased gamma-GT is not clinically significant. "

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.