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Test Code GTGS or LAB879 Glucose Tolerance, 1-Hour Gestational Screen - ACOG (1 hr, 50 gm), Serum or Plasma

Important Note

By appointment only. Please call Bronson Central Scheduling at 269-341-8700 to schedule this test.

Patients are permitted to bring in their own glucose powder if the product is Fresh Test 50-gram powder.

 

Specimen Requirements

Patient Preparation

  • Fasting is not required.
  • No formal dietary preparation is recommended unless it is estimated that less than 150 grams of carbohydrates per day has been consumed.
Container Type:

Optimal: Mint

 

Acceptable*: Gold or Red

 

*Serum samples are not preferred because they must be allowed to clot before centrifugation. Prolonged contact between red cells and serum can falsely lower glucose values.
Optimal Collection Volume: 

4.5mL; full tube
Minimum Volume:

1 mL whole blood
Collection Instructions:
  1. Gently invert the sample 5-6 times after collection.
  2. Give the patient a 50-gram dose of glucose beverage, noting the time of ingestion (the patient must drink the entire beverage within 5 minutes).
  3. Draw blood specimen one hour after ingestion of glucose beverage.
  4. Label the specimen with the time of draw.
  5. Indicate if the patient is pregnant on the request
Specimen Transport:

Refrigerate
Processing Instructions: 
  1. If serum, allow the specimen to clot for 30 minutes.
  2. Centrifuge specimen within 2 hours of collection.
  3. After centrifugation, specimen tubes without a gel barrier should have the serum or plasma aliquoted to a false bottom container.
  4. Keep the serum or plasma refrigerated until testing can be performed.

Specimen Stability

Specimen Type Temperature Time
Serum* Refrigerated 3 days
Room Temperature 8 hours

*Note: Heparinized plasma in gel separator tubes is less stable than serum and is only suitable for add-on testing up to 2 days following sample collection.

Specimen Rejection Criteria

Hemolysis Mild OK; Moderate OK; Gross Reject
Lipemia Mild OK; Moderate OK; Gross Reject
Icterus Mild OK; Moderate OK; Gross Reject
Other Quantity not sufficient

Methodology

Roche Cobas - Enzymatic with hexokinase

Reference Ranges

65-139 mg/dL

Day(s) Performed

Monday through Friday, by appointment only

Expected TAT

Same day

Performing Laboratory

Bronson Laboratory, Chemistry - Kalamazoo, Battle Creek, Paw Paw, South Haven

Sample Retention Time

7 days

CPT Code

82950

LOINC Code

N/A