Test Code GTT5HR Glucose, Tolerance, 5 Hour Hypoglycemia (GTT)
Performing Location
Specimen Collection Information
| Specimen | Min. Test Volume | Collection Container | Special Handling |
|---|---|---|---|
| Blood | 0.1 mL | Light Green (lith. heparin) top Gold top Marble Red top |
Reference Ranges & Critical Values
| Assay | Gender | Age Range | Normal Range | Critical Values | Units |
|---|---|---|---|---|---|
| GTT5HR | ALL | 0 Minutes – 150 Years |
Results interpreted by Physician |
<45 >500 |
mg/dL |
Collection Instructions
Refer to Glucose Tolerance Protocols for additional instructions.
-
Confirm that the patient has fasted 10-16 hours.
-
Collect urine sample and run dipstick urine test. If test is positive, consult physician to determine whether to continue tolerance test.
-
Draw fasting blood sample in green top tube or use hemmocue finger stick. Save 1 mL of serum frozen for possible insulin assay.
-
Have patient drink 225mL (7.5oz) of Dextol Glucose Tolerance Beverage for a dose of 75 grams of glucose. See dosage chart if patient weighs less than 91 lbs. Record time.
-
Patient should be instructed to continue fasting with limited physical activity for the duration of the test. Monitor patient during test for symptoms of hypoglycemia.
-
If symptoms appear, notify physician. Insulin and glucose levels determined at the time of symptoms are most diagnostic. Physician should determine whether to obtain sample at this time and/or continue test.
-
Draw blood samples 1, 2, 3, 4 and 5 hours from the time the Dextol was given. Save 1 mL of serum from each specimen frozen for possible insulin assay.
Specimen Stability
3 days at 2-8°C
Day(s) Performed
Monday - Sunday
CPT
82951 + 82952
LOINC
50588-3