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Glucose Tolerance Test, Pregnancy
| Item | Value | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Approval req'd? | No | ||||||||
| Available Stat? | No | ||||||||
| Test code | OGTP | ||||||||
| Test group | Glucose | ||||||||
| Performed by | Parnassus & Mt. Zion Chemistry | ||||||||
| In House Availability | Test available at ACC 0730-1530 weekdays. Test available at 2230 Post St. 0800-1400 weekdays. |
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| Method | Oxygen consumption (O2 electrode with glucose oxidase) | ||||||||
| Patient Preparation | The patient should be instructed by the care-giver to eat a normal diet containing at least 150 g of carbohydrate and carry out normal physical activity for at least 3 days prior to the morning of the test, which is administered after an 8-14 hour. fast. | ||||||||
| Collection Instructions | For outpatients, Please schedule in advance with the ACC outpatient lab, x32736, or Post St. lab, 415-885-7531. Outpatient testing at ACC available 0730-1530 weekdays, and at 2330 Post St. 0800-1400 weekdays. The patient should be seated for the test and should not smoke. Collect all samples in Gray top tubes<>/b> Obtain a fasting sample and send to lab for stat testing. If the patient has been screened using the 1-hour 50-gram test (GLT1), the Clinic will determine what the fasting level should be in order to proceed with the 3-hour 100 gram test. If the 1-hour 50-gram test result was ≥ 180 mg/dL the fasting glucose should be < 95 mg/dL to proceed with the 3-hour test. If the 1-hour 50-gram test result was 140-179 mg/dL, the fasting glucose should be < 110 mg/dL to proceed. If the fasting glucose is over these levels, do not proceed but refer the patient back to the Diabetes Clinic. If the patient has not been screened using the 1-hour 50-gram test (or the Clinic does not indicate this), the fasting level to proceed with the 3-hour test must be ≤ 110 mg/dL. |
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| Container type | Gray top | ||||||||
| Amount to Collect | 1 mL blood Click here for Microdetermination info | ||||||||
| Sample type | Serum | ||||||||
| Preferred volume | 0.5 mL serum | ||||||||
| Min. Volume | 0.2 mL serum Click here for Microdetermination info | ||||||||
| Units | mg/dL | ||||||||
| Normal range |
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| Synonyms | Diabetes mellitus | ||||||||
| Stability | Room temperature 8 hours, refrigerated 2 days | ||||||||
| Additional information | All patients should be screened with a fasting glucose: 90% of patients whose 2 hour level is > 199 mg/dL have fasting hyperglycemia, obviating the need for tolerance testing. Glucose tolerance beverages are available in 100 g bottles (10 g/fl. oz. at 10 oz.) at ACC, and 100 g and 50 g bottles (10 g/fl. oz., 5 g/fl. oz.both 10 oz.) at Post St. Note: A positive diagnosis requires that two or more thresholds be met or exceeded. Reference values for the 100 gram 3 hour GTT are taken from American College of Obstetricians and Gynecologists. Committee opinion no. 504: screening and diagnosis of gestational diabetes mellitus. Obstet Gynecol 2011;118:751–3. Additionally, there is controversy regarding the approaches used to diagnose gestational diabetes Blackwell SC. Counterpoint: enough evidence to treat? The American College of Obstetricians and Gynecologists guidelines. Clin Chem. 2012 Jul;58(7):1098-100. |
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| Last Updated | 12/19/2012 2:01:03 PM | ||||||||
| Entry Number | 430 | ||||||||
| Lab Procedure Link | Click here for Procedure |
If you have additional questions regarding this test, please call: 415-353-1667