University of Iowa
Diagnostic Laboratories
(UIDL) Test Directory

319-384-7212 (local)
1-866-844-2522 (toll free)


Gamma Glutamyl Transpeptidase (GAMMA-GT) Order Code: GGT
Order Form: Laboratory Requisition
Specimen:
Plasma
Collection Medium:
Plasma separator tube
Alternate
Collection Media:
Call laboratory for additional acceptable specimen collection 
containers.
Minimum:
2 ml whole blood in light green top tube or 2 microtubes for pediatric 
patients
Testing
Schedule:
24 hrs/day, 7 days a week, including holidays.
Analytic Time:
2 hours (upon receipt in laboratory)
Reference Range:
Male   8-61 u/l
Female 5-36 u/l
Comments:
Elevated by drugs such as Phenobarbital and Dilantin.

Please print, complete and submit the Advance Beneficiary Notice 
(ABN) along with the Laboratory Requisition before shipping the 
specimen.
Test
Limitations:
Criterion: Recovery within plus or minus 10% of initial value.

Icterus: No significant interference up to an I index of 20 mg/dl for 
unconjugated bilirubin (approximate unconjugated bilirubin 
concentration:20 mg/dl).

Hemolysis: No significant interference up to an H index of 200 mg/dl 
(approximate hemoglobin concentration: 200 mg/dl).

Lipemia (Intralipid): No significant interference up to an L index of 
1000 mg/dl (approximate triglycerides concentration: 2000 mg/dl).There 
is poor correlation between turbidity and triglycerides concentration.

Reference:
Glick MR, Ryder KW, Jackson SA. Graphical Comparisons of Interferences 
in Clinical Chemistry Instrumentation. Clin Chem 1986;32:470-474.
Methodology:
Enzymatic
Sample
Processing:
Centrifuge at 3000 RPM for 10 minutes.
Aliquot plasma into labeled container and cap.
Sample
Storage:
Refrigerate.
Transport
Instructions:
Place requisition into outside pocket of bag.
Place specimen into zip-lock type bag, seal bag.
Transport in cooler with refrigerated coolant packs.
CPT Code:
82977

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Updated: 09/18/2006