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Labcorp Oklahoma, Inc.
Test Directory


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Glucose Tolerance (3 Hour) Gestational Diabetes Panel

Order Name GTT PREG
Test Number: 2023550
Revision Date 05/20/2021
Test Name Methodology LOINC Code
Gestational Fasting Glucose
Hexokinase 1558-6 
Gestational 1hr Glucose
Hexokinase 20438-8 
Gestational 2hr Glucose
Hexokinase 20436-2 
Gestational 3hr Glucose
Hexokinase 20437-0 
SPECIMEN REQUIREMENTS
Specimen Specimen Volume (min) Specimen Type Specimen Container Transport Environment
Preferred 2 mL (0.5) Plasma Sodium fluoride (gray top) Refrigerated
Alternate 1 2 mL (0.5) Plasma Lithium Heparin PST (Light Green Top) Refrigerated
Alternate 2 2 mL (0.5) Serum Clot Activator SST Refrigerated
Instructions If the patient is not pregnant please use Glucose Tolerance (2 Hour Only) order name GLUC 2 HR.

Must schedule collection Monday thru Friday from 8am to 12pm. Overnight fasting required. Nothing by mouth except water during testing.
Collect a full Sodium fluoride (gray top) tube to for each time interval. 2mL (0.5) of Plasma is required for each glucose interval.
Collect and label a baseline gray top tube for the Fasting Glucose. Then give the patient 100 grams Glucola. Collect and label a gray top for 1 hour, 2 hours and 3 hour interals after the ingestion of the Glucola.
Stability: Ambient 8 hours, Refrigerated 7 days, Frozen 1 month
Fluoride preserved plasma samples are stable at room temperature for 24 hours
GENERAL INFORMATION
Testing Schedule Daily 
Expected TAT 1-2 days  
Clinical Use Used in diagnosing gestational diabetes, and to predict perinatal morbidity, risk of fetal abnormality and perinatal mortality. 
Notes For more information on this test, access our "Specialized Tests" section.
CPT Code(s) 82951; 82952
Lab Section Chemistry