Synonyms: 3HR GTT

CPT 4 Code: 82951

Test Order Mnemonic: GTT 3HR

Test Includes: Serum or plasma glucose and urine glucose

Lab: Clinical Chemistry

Request Form: Routine Chemistry Form 1

Patient Preparation: Fasting 8 hours prior to beginning the test.

Collection: Routine venipuncture

Storage Instructions: Centrifuge the specimen to separate serum from cells within 2 hours of collection; if using grey-topped tubes, plasma need not be separated if specimens are delivered to the laboratory within 8 hours of collection. Refrigerate samples at 2-8°C

Causes for Rejection: Gross hemolysis, improperly labeled specimens, collection time not written on tubes or urine containers. See special instructions.

Availability: Samples are received 24 hours per day at Sample Management, Room 5.136 McCullough.

Turnaround Time: Routine: 4 hours; STAT: 1 hour

Special Instructions: All specimens must have collection time on tube and urine container (e.g., 1/2 hr, 1 hr, 2 hr, 3 hr, etc.). Write times of collection for each sample on the request form.

Specimen: Blood and urine

Volume: 7 mL blood + 10 mL urine

Minimum Volume: 0.5 mL serum or plasma + 5 mL urine

Container: SST (gel barrier) or gray-topped ( sodium fluoride) tube for blood sample and plastic container for urine aliquot

Reference Ranges:

Test Method: End Point Colorimetric, oxidase

Reviewed/revised April 2007 by P. Harris