GTT 1 Hour (100 gram dose for pregnancy)

Label Mnemonic:	GT1OB
Epic code:	LAB8761
Downtime form:	Doctor/Provider Orders - Pathology Core and Specialty Care Nursery

Chemistry
6240 RCP
356-3527

Specimen(s):

Plasma

Collection Medium:

Gray top tube 6 mL (Na Fluoride)

Alternate Collection Media:

Call laboratory for additional acceptable specimen collection containers.

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

CPT Code:

82951 for the first 3 specimens and 82952 for each additional specimen