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Lab Manual for SFGH

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GLUCOSE TOLERANCE TEST, ORAL

Item Value
Available Stat? No
Test code see chart in "Additional Information", below
Performed by? Chemistry
Sendout? no
Price range $$$
In House Availability Monday - Thursday, 8:30 am. Patients must arrive promptly. Test not performed on Fridays.
Patient Preparation 1. Patients must be ambulatory and must not require constant observation.

2. Patients must be properly prepared for the three hour glucose tolerance test (GTGD). The test should begin in the morning after an overnight fast of between 8 – 14 hours, and after at least 3 days of unrestricted diet and unlimited physical activity.

3. Patients must be at the outpatient department (OPD, 1C33) Clinic Laboratory promptly at 8:30 am, Monday - Thursday (test not performed on Fridays). Tests on patients will be started only at that time. The oral glucose load will be administered in the OPD Clinic Laboratory.

4. Glucose solution must be consumed within 5 minutes. Blood will be drawn at appropriate times after dosing.

5. The patient is not permitted to smoke during the testing period.

6. Send properly filled out requisition for glucose tolerance test with the patient.
Special instructions Tolerance tests involving patients with suspected hypoglycemia and/or requiring the administration of hypoglycemic agents or other drugs must be performed on the ward by the ward staff to ensure appropriate observation, safety, and availability of emergency treatment, if necessary.
Synonyms Oral Glucose Tolerance Test;
Additional information TEST INFORMATION: For investigation of suspected glucose intolerance, the glucose tolerance test should be ordered only to evaluate elevated fasting glucose levels, or to confirm abnormal or equivocal 2-hr postprandial glucose levels.

The oral glucose tolerance test should not be performed on stabilized patients with persistently elevated glucose levels because these patients will all have abnormal glucose tolerance test values.
Test
(Computer Code)
Reason Dose
(Oral
Glucose)
Blood
Draws
Fasting?
Y/N
1 hr post load
(GT50)
Gestational screen
(prenatal screen)
50 g 1 hr post N
Glucose tolerance
(GTGD)
fasting and 3 hour
Gestational
diagnosis
(pregnant patients)
100 g Fasting
(baseline);
1, 2, & 3
hrs
Y
Glucose tolerance
(GT75)
2 hour
Adult; including
post partum
75 gm Fasting; 2
hrs post
Y
References 1. Diagnosis and Classification of Diabetes Mellitus. American Diabetes Association: Diabetes Care. Volume 29, Supplement 1, January 2006.

2. Sacks et al., Guidelines and recommendations for laboratory analysis in the diagnosis and management of diabetes mellitus, Clin Chem 48:3; 436-472, 2002.
CPT coding 82951
Last Updated 11/12/2008 11:24:35 AM
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