GTT 2 Hour (100 gram dose for pregnancy)

Label Mnemonic:	GT2OB
Epic code:	LAB8762
Order form:	Laboratory Requisition
Supply order:	Supply Order Form
Billing:	Billing Policies
CPT code:	82951 for the first 3 specimens and 82952 for each additional specimen

Specimen(s):

Plasma

Collection Medium:

	or
Gray top tube 6 mL (Na Fluoride)	or	Plasma Separator Tube 4.5 mL (Centrifuge Immediately)

Minimum:

3 mL plasma in gray top tube

Testing Schedule:

24 hrs/day, 7 days a week, including holidays.

Turn Around Time:

1 hour (upon receipt in laboratory)

Reference Range:

Glucose, Fasting (100 gram dose for pregnancy) < 95
GTT 1 hour (100 gram dose for pregnancy) < 180
GTT 2 hour (100 gram dose for pregnancy) < 155
GTT 3 hour (100 gram for pregnancy) < 140
GTT 1 Hour, Non-fasting (50 gram dose for pregnancy) < 140

Reference range based on: ACOG Practice Bulletin.  Clinical Management 
Guidelines for Obstetricians-Gynecologists.  Gestational Diabetes 
Mellitus.  Number 190, February 2018.

Comments:

Collect all specimens in gray top tube on patient care area and hold (sodium fluoride anticoagulant). Deliver all specimens simultaneously. Microtube specimens must be scheduled with the lab in advance and delivered immediately after drawing.

Test Limitations:

Icterus: No significant interference up to an I index of 60 (approximate conjugated and unconjugated bilirubin concentration: 60 mg/dL).

Hemolysis: No significant interference up to an H index of 1000 (approximate hemoglobin concentration 1000 mg/dL).

Lipemia (Intralipid): No significant interference up to an L index of 1000 (approximate triglycerides concentration 2000 mg/dL). There is poor correlation between turbidity and triglycerides concentration.

Methodology:

Hexokinase/UV Test

Instructions:

Gray top (Na Fluoride) collections: Transport whole blood to the laboratory within 24 hours.

Sample Processing:

Centrifuge at a speed and time necessary to get barrier separation of plasma/serum and cells within 1 hour of collection.
Separate plasma or serum into labeled container and cap.
Label transport tube with two patient identifiers, date and time of collection.

Sample Storage:

Refrigerate.

Transport Instructions:

Place labeled specimen into zip-lock type biohazard bag; seal bag.
Place completed requisition into outside pocket of bag.
Transport in cooler with refrigerated coolant packs.