Gamma-Glutamyltransferase (GGT)

CPT Code(s):


Specimen Requirements:

Type: Serum or plasma

Container/Tube: Serum gel or EDTA plasma

Sample Volume: Submit full tubes.

Minimum Volume: 0.5 mL serum or plasma


  1. Send specimens in their original tubes.
  2. Centrifuge tubes if there is a delay in transport of more than 1 hour.

Storage: Samples are stable for up to 30 days at 2 – 8ºC.

Unacceptable Conditions: Samples with moderate or marked hemolysis will be rejected.

Specimen Retention Time: 5 days


Gamma-glutamyltransferase measurements are used in the diagnosis and treatment of liver diseases such as alcoholic cirrhosis and primary and secondary liver tumors.


This gamma-glutamyltransferase (GGT) procedure is a modification of the Szasz procedure. GGT catalyzes the transfer of the gamma-glutamyl group from the substrate, gamma-glutamyl-3-carboxy-4-nitroanilide, to glycylglycine, yielding 5-amino-2-nitrobenzoate. The change in absorbance at 410/480 nm is due to the formation of 5-amino-2-nitrobenzoate and is directly proportional to the GGT activity in the sample.


Within 24 hours

Reference Values:

Adults: 9 – 64 U/L