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Test Code LAB4449 Glucose Tolerance Test (GTT), 2 Hour, ADA (American Diabetic Association)

Important Note

Non-maternal Glucose testing

Testing includes the following:

  • Glucose Tolerance Testing Fasting ADA (fasting specimen)
  • Glucose Tolerance Testing 2 Hour ADA (Drawn at 2 hours post Glucola)

Useful For

Used to establish the diagnosis of diabetes mellitus, evaluate disorders of carbohydrate metabolism; acidosis and ketoacidosis; dehydration, coma, hypoglycemia, insulinoma or neuroglycopenia.

Performing Laboratory

Asante Rogue Regional Medical Center / Asante Three Rivers Medical Center

 

Performing Department

Chemistry

Specimen Required

Sodium Fl (NaF) Gray top tube  Preferred

Lithium Heparin Green top tube (must be centrifuged within 1-2 hrs, preferably within 1 hr)

Yellow (Gold) top tube (SST)

 

Outpatient clients MUST draw SST

 

Collection:  
1. Collect fasting specimen

     2. Administer dextrose*

     3. Collect a second specimen 2 hours post dextrose.

 

Dosage:
*75 gm dextrose after normal fasting glucose result. 

NOTE: 

  • 15 years of age (or younger) the dosage should be 1.75 gm/kg. Refer to Pediatric Weight Correction Table in iPassport: PHLEB 16: Oral Glucose Tolerance (OGTT) Test Collection Procedure.
  • The physician will be contacted prior to proceeding with tolerance if fasting glucose is above 125mg/dL.

Patient should be fasting 12 hours prior to test. 

Patient should have had adequate food intake with at least adequate carbohydrates for 3 days prior to test. 

NO CAFFEINE, NICOTINE OR EMOTIONAL STRESS until all specimens have been collected.

 

Avoid drugs which:
     1. Increase blood sugar:  birth control pills, salicylates, diuretics, alcohol, steroids, etc.
     2. Decrease blood sugar: 
                insulin (omit A.M. dose at least), sulfonylureas (omit for 3 days),
                propranolol (omit for 24 hours).

 

Activities: Generally patient should be seated, but minimal walking is permitted.

 

Note: Other chemistry tests cannot be analyzed using the Gray NaF tube.

Specimen Stability

Centrifuge collection tube within 1 hour of collection (no longer than 2 hours). 

Stable 8 hours at room temperature, 24 hours refrigerated at 2°- 8°C on separated SST, 
48 hours if serum aliquoted and stored at 2°-8°C. 

If centrifuge not available, the sample must be drawn in a gray sodium fluoride (NaF) tube.

Reject Due To

Hemolysis

Lacking Two Patient Identifiers:

         1-Patient's First & Last name 

         2-Patient's Date of Birth

Day(s) Performed

Monday through Sunday 

Method Name

Oxygen Rate Electrode

CPT Code Information

82947  -  Glucose; quantitative, blood

82950  -  Glucose; post glucose dose

Billing Code

2050615, 2050649