Glucose 3 Hours OB

Test Code

GLUC 3 OB - NOCO

Alias/See Also

GTT

CPT Codes
82951, 82952

Preferred Specimen

1.0 mL plasma from Green top (Lithium Heparin)

Minimum Volume

0.5 mL

Other Acceptable Specimens

1.0 mL serum from Serum Gel or Red Top

Instructions

A copy of the Glucose Tolerance Patient Information (English / Spanish) should be given to the outpatient.

Draw blood early in morning from a patient fasting at least 8 hours.
Perform glucose monitor from green-top (LiHep) tube or on a fingerstick specimen before giving patient 100 g Glucola^TM supplied.
For outpatients drawn at an NCMC service center: If fasting glucose monitor or fingerstick glucose is >140 mg/dL, notify North Colorado Medical Center Chemistry Department at 970-810-6412 and forward fasting tube for a STAT Glucose. If this value is >140 mg/dL, do not proceed with procedure. Chemistry department will notify a pathologist, and he will contact patient’s physician. Patient will be asked to wait (if outpatient) until physician can be contacted.
For patients drawn at remote clinics: A fasting glucose monitor or fingerstick glucose is >140 mg/dL is diagnostic of diabetes mellitus. However, finger stick glucose value is not as accurate as confirmatory glucose value from a standard chemistry analyzer. Therefore, dependent on the magnitude of finger stick glucose value, a clinic physician may make the determination as to whether to send a fasting specimen to the laboratory (eg, for a very high finger stick value that is probably diagnostic for DM) or to proceed to 2 hour GTT (eg, a finger stick value that is in the vicinity of 140 mg/dL)
If fasting glucose is <140 mg/dL, proceed as follows:
Instruct patient to drink 300 mL (10 oz. cup) of water. Administer 100 g of Glucola^TM. Patient must complete ingestion of Glucola^TM within 5 to 10 minutes.
Record the time of the start of Glucola^TM (all timings proceed from this point).
Draw blood at 1, 2 and 3 hours after ingestion of 100g Glucola^TM.
Label tubes with the patient’s full name, fasting, 1, 2 and 3 hour, and date and time of collection.

If symptoms such as pallor, sweating, fainting, or marked nausea develop during test, procedure should be discontinued and repeated at another time.
For further information see Patient Preparation for Glucose Tolerance Testing in Specimen Collection and Preparation.

Specimen Stability

Temperature	Time
Refrigerated	72 hours

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)

Gross hemolysis
For NCMC only: Gross lipemia if plasma - Serum specimen needed if Grossly Lipemic.

Methodology
Hexokinase Bichromatic Endpoint

Setup Schedule

Monday through Sunday; Continuously

Report Available

Same day

Reference Range

Fasting: ≤95 mg/dL
1 hour: 70-179 mg/dL
2 hour: 70-154 mg/dL
3 hour: 70-139 mg/dL
Critical value (automatic call-back): <50 or >490 mg/dL

Clinical Significance

Gestational diabetes is carbohydrate intolerance of variable severity with onset or first recognition during the present pregnancy. The diabetes usually disappears after the birth of the baby but may be associated with an increased risk of diabetes in the mother.

Performing Laboratory
Banner Fort Collins Medical Center Laboratory
Mckee Medical Center Laboratory
North Colorado Medical Center Laboratory
Summit View Laboratory

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.