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Test Code 1770 Glucose Challenge Test, 50 G/1 Hour (Gestational Diabetes Screen), Plasma

Performing Laboratory

Barnes-Jewish Hospital Laboratory


Enzymatic (Hexokinase)

Literature References:

Package insert: Glucose/HK, Roche Corporation, 1/2006.

Specimen Requirements

This test is utilized in screening for gestational diabetes among women with appropriate risk factors, and is usually performed during weeks 24 to 32 of pregnancy.


Patient Preparation:

Fasting is not required.


Collection Procedure:

1. Give patient 50 g glucose tolerance beverage.
2. Draw specimen 1 hour post consumption.


Specimen Type: Plasma

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

Specimen Volume: Full tube


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

70-140 mg/dL

Critical result (automatic call-back): ≤50 mg/dL or ≥450 mg/dL

A glucose value of >140 mg/dL generally indicates the need for a full diagnostic tolerance test. See #1970 Glucose Tolerance Test, 100 G/3 Hour (Gestational Diabetes Diagnostic), Plasma.

Literature References:

1. Diabetes Care 2005;28:Supplement 1,S37-S42.

2. Report of the expert committee on the diagnosis and classification of diabetes mellitus. Diabetes Care 2000;23: Supplement 1,S4-19.

Test Classification and CPT Coding


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

Specimen Transport Temperature


Special Instructions

LOINC Code Information

Name LOINC Code
Glucose- 1 hour post 50 g glucose PO 1504-0