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Labcorp Oklahoma, Inc.
Test Directory


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Glucose Tolerance (2 Hour) w/o Urine

Order Name GTT 2 HR
Test Number: 2016800
Revision Date 05/20/2021
Test Name Methodology LOINC Code
Glucose Fasting
Hexokinase 1558-6 
Glucose 1 Hour Tolerance
Hexokinase 20438-8 
Glucose 2 Hour Total
Hexokinase 20436-2 
SPECIMEN REQUIREMENTS
Specimen Specimen Volume (min) Specimen Type Specimen Container Transport Environment
Preferred 1 mL (0.5) Plasma Sodium fluoride (gray top) Refrigerated
Alternate 1 1 mL (0.5) Plasma Lithium Heparin PST (Light Green Top) Refrigerated
Alternate 2 1 mL (0.5) Serum Clot Activator SST Refrigerated
Instructions Fasting overnight and during test. Patient may have water.
Draw fasting specimen. Adults: Give 75 grams of glucola. Children: Adjusted amount of glucola to be calculated by lab. Call (918) 744-2500.
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 Mon - Fri 
Expected TAT 1-2 days  
Clinical Use Criteria for Diagnosis of Diabetes from the American Diabetes Association recommends Random plasma glucose >200 mg/dl with symptoms (polyuria, polydypsia, and unexplained weight loss) repeated to confirm on subsequent day, or Fasting plasma glucose>126 mg/dl repeated to confirm, or 2hr plasma glucose <200 mg/dl post 75g glucose challenge repeated to confirm. 
Notes For more information on this test, access our "Specialized Tests" section.
CPT Code(s) 82951
Lab Section Chemistry