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HelpTest Code GEDS Gestational Diabetes Screen (GDS)
Specimen and Container/Tube
Specimen Type: Plasma
Preferred Specimen: Grey Top, NaF/K-Oxalate
Other Acceptable specimens: None
Collection Instructions
- Collect specimen per standard laboratory collection procedures.
- Glucose Beverage Ingestion: Patient drinks the entire bottle of refrigerator-temperature Glucocrush® 50 solution within 5 minutes. Timing begins the moment the patient starts drinking. Patient is to remain seated as much of the time as possible and is not to chew gum, smoke, drink or eat during the test. Ingestion of small amounts of water is acceptable
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Prepare for Blood Draw
- If the patient feels ill, or if she regurgitates, the phlebotomy staff should be notified immediately in order to contact the patient's physician for further instructions. If the physician instructs to have the test completed, this will be noted on the chemistry requisition.
- Patient will return for blood draw no more than 55 minutes after the ingestion.
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Specimen Collection
- Sample is drawn using a Gray Top Tube, exactly 60 minutes after the patient started drinking the Glucocrush® 50. Sample tube is labeled “1 hr GDS” and bring immediately to the lab for testing.
- All blood samples are brought immediately to the lab for testing.
Specimen Handling and Transport Instructions
UCMC Onsite Instructions:
- Collect specimen per standard laboratory collection procedures.
UCMC Offsite and UC MedLab Outreach Instructions:
- Collect specimen per standard laboratory collection procedures.
- Centrifuge specimens at >2500 x g for 10 minutes at room temperature within 2 hours of collection.
- Aliquot removed plasma into a plastic tubes containing a minimum of 0.2 mL of specimen.
- Plasma samples must then be sent room temperature at 20 - 25oC
Reference Values
|
Test |
Age |
Sex |
Reference Range |
|
GEDS |
All |
All |
≤ 140 mg/dL |
Volume
Preferred Volume: 0.5 mL
Minimum Volume: 0.2 mL
Specimen Stability
|
Storage Temperature |
Stability |
|
Room temperature |
3 days |
|
Refrigerated |
3 days |
|
Frozen |
Not acceptable |
Rejection Criteria
- Common specimen rejected situations include: incorrect specimen type, insufficient volume, missing or incomplete specimen identifiers, incorrect specimen transport, or specimens outside stability limits.
- Specimens that are clotted or grossly hemolyzed.
- Specimens that were transported unspun/whole blood and draw time is greater than 6 hours
Critical Values
|
Analyte |
Unit |
Low |
High |
Age |
|
Glucose |
mg/dL |
<40 |
>500 |
>14 days |
Test Components
Glucose
Clinical Indications
The GDS test is a screening test for possible diabetes in pregnant patients. Without regard to prior food intake, venous plasma glucose is measured, usually between 24 and 28 weeks of pregnancy, at an interval of one hour following an oral dose of 50 mg of glucose.
Methodology
Enzymatic Method with hexokinase (Roche Diagnostics)
CPT Codes
82947
LOINC Codes
TBD
Additional Information
- Results should always be assessed in conjunction with patient's medical history, clinical examination and other findings.
- Interpretation of Results: Any result equal to or greater than 140 mg/dL, is considered abnormal. This level is recommended as a threshold to indicate the need for a full diagnostic glucose tolerance test, e.g. the Gestational GTT. The GDS should identify the majority of women with gestational diabetes mellitus (GDM), although some false negative may occur, especially in patients who are not fasting.
Turnaround Time
Turnaround times are relative to the time the specimen is received in the test laboratory.
STAT Turnaround Time: Not Available as STAT test
Routine Turnaround Time: 4 hours
Testing Schedule: 24/7
Synonyms/Keyword Search
GDS, DM, GDM, IFG, IGT
Last Review Date
6/4/2025