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Test Code 1970 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, 1/2006.

Specimen Requirements

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

 

Collection Procedure:
Note:
 1. Glucometer pre meter check is not for diagnostic purposes per American Diabetes Association; Diabetes Care:19(Suppl):562-6.

2. This test is used to diagnose gestational diabetes if indicated by screening test.

 

Obtain glucometer reading and proceed as follows:

 

If glucometer glucose is <150 mg/dL
1. Draw fasting venous specimen.
2. Give patient 100 g glucose tolerance beverage.
3. Draw venous specimens at 1-, 2-, and 3-hours post consumption.

 

If glucometer glucose is >150 mg/dL
1. Do not give glucose tolerance beverage.
2. Draw a venous specimen. Send STAT to Barnes-Jewish Hospital Laboratory for #1857 Glucose, Fasting.

 

If STAT Glucose, Fasting is <140 mg/dL
1. Give patient 100 g glucose tolerance beverage.
2. Draw venous specimens at 1-, 2-, and 3-hours post consumption.

 

If STAT Glucose, Fasting is >140 mg/dL
Contact physician before proceeding.

 

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

Reference Values

100 G/3 hour (Gestational Diabetes Diagnostic)

Normal range:  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.

Current interpretive data was last revised on 1/9/2017.

Test Classification and CPT Coding

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

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
Analyte Stability:

See Analyte Stability Chart in Special Instructions.

Laboratory Processing Instructions:
Test performed in BJH Chemistry. Centrifuge upon receipt. Deliver to the Modular workstation in Chemistry or North Campus Laboratory. Completed specimen is stored refrigerated for 1 week.

Specimen Transport Temperature

Ambient

Special Instructions

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