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Test Code GTT3HOUR Glucose, Tolerance, 3 Hours (GTT)

Important Note

*An extra serum sample for insulin must be drawn and frozen with each tolerance sample*

Specimen Collection Information

Specimen  Min. Test Volume Collection Container Special Handling
Blood 0.1 mL Gold top
Marble Red top
 

Reference Ranges & Critical Values

Assay Gender Age Range Normal Range Critical Values Units
GTT3HOUR ALL 0 Minutes – 150 Years   <45
>500
mg/dL

Collection Instructions

MATERIALS:

  • One bottle of lemon/lime Dextol, 100g.

DIRECTIONS:

  1. A fasting blood sugar will be completed before the patient receives the glucocrush.
    1. Perform a finger stick to check the patient's glucose level using the Hemocue glucometer.
    2. The patient's glucose level should be 126 mg/dL or lower in order to continue with testing.
    3. If the patient's glucose level is higher than 126 mg/dL, the testing will not be performed. The patient will be informed that the ordering physician will be notified and they will contact the patient with further instructions.
  2. Instruct patient to drink 100g glucose in about a 5-minute period. Glucose drink must be measured and administered only by a phlebotomist trained in this procedure.
  3. Note the time that the dose is finished, and make arrangements to draw 1 hour, 2 hour, and 3 hours after that time. RECORD TIMES on appropriate computer labels.
  4. Patient should remain seated in the Laboratory, continue fasting, and not smoke during the test. Ask the patient to notify Lab if they begin to feel ill.
  5. Draw remaining blood samples, indicate times drawn on tubes.

Day(s) Performed

Monday - Friday

Specimen Stability

3 days at 2-8°C

CPT

82951

LOINC

50586-7