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Test Code LAB5713 Glucose Tolerance Test, 100 G/3 Hour (Gestational Diabetes Diagnostic), Plasma

Performing Laboratory

Barnes-Jewish Hospital Laboratory

Methodology

Enzymatic (Hexokinase)
Literature References:

Package insert: Glucose/HK, Roche Corporation, 06/2018

Specimen Requirements

Patient Preparation:
An 8 to 14 hour fast after 3 days of adequate carbohydrate loading (>150 g/day) is required.

 

Collection Procedure:

  1. Draw fasting specimen.
  2. Give patient 100 g glucose tolerance beverage.
  3. Draw specimen 1 hour post consumption.
  4. Draw specimen 2 hours post consumption.
  5. Draw specimen 3 hours post consumption.

Specimen Type: Plasma

Container/Tube: Grey top (potassium oxalate/sodium fluoride)

Specimen Volume: Full tube

 

Additional Information: Draw times are required.

Day(s) Test Set Up

Monday through Sunday
Turnaround Time:
STAT: 1 hour after receipt in laboratory
Routine: 2 to 4 hours after receipt in laboratory

Test Classification and CPT Coding

82951-Glucose tolerance, 3 specimens
82952-Glucose tolerance, each additional specimen

Reference Values

100 G/3 hour (Gestational Diabetes Diagnostic)

Diagnostic criteria generally require that 2 or more of the following criteria be met:

Fasting:  ≥ to 95 mg/dL

1 Hour:   ≥ to 180 mg/dL

2 Hour:   ≥ to 155 mg/dL

3 Hour:   ≥ to 140 mg/dL

 

Reference Interval Info:  Harper,L.M.,et al.  Carpenter-Coustan Compared With National Diabetes Data Group Criteria for Diagnosing Gestational Diabetes.  Obstetrics & Gynecology 2016: 127 (5): 893-898.

Diabetes Care 2020: 43 (Suppl 1): S14-31

Specimen Transport Temperature

Ambient

Additional Information

For BJH Laboratory Use Only
Alternate Tube:

1 dark green-top (lithium heparin) tube

1 lavender-top (EDTA) tube

1 mint green-top (lithium heparin) tube

1 red-top tube

Laboratory Processing Instructions:

Test performed in BJH Core Lab.  Processed by automated line for delivery to the Cobas 8000. Completed specimens are stored refrigerated for 5 days. 

Test performed in South County Siteman and Ambulatory Cancer Building Lab.  Centrifuge sample and deliver to the Cobas.  Completed specimens are stored refrigerated for 5 days. 

Special Instructions

See Analyte Stability Chart under General Information for a complete list.

LOINC Code Information

Name LOINC Code
Glucose in Blood 2339-0
Fasting Glucose 1558-6
Glucose- 1 hour post 100 g glucose PO 1501-6
Glucose- 2 hours post 100 g glucose PO 1514-9
Glucose- 3 hours post 100 g glucose PO 1530-5