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Test Code LAB4097 GTT, 1 HOUR

Specimen Type

Preferred Specimen: Lithium Heparin Plasma (Mint Green Top, Dark Green Top)
Alternative Specimen: Serum (SST, Gold, Corvac, Tiger, Red Top Tube) Sodium Flouride (Gray Top Tube)

Specimen Volume

2 mL each specimen

Turnaround Time

STAT: 1 hour after receiving all specimens
Routine: 4 hours

Test Schedule

Daily 

CPT Codes

82950

Collection Instructions

Draw fasting specimen just prior to 50 gram glucose load. Draw another specimen after 1 hour. Clearly label each specimen.

Minimum Volume

0.3 mL each specimen

Sample Stability

3 days if separated from the cells within 30 minutes of collection

Method

Hexokinase

Test Components

Glucose, fasting, mg/dL; Glucose, 60 minutes, mg/dL

Patient Prep

This test should be done in the morning after an overnight fast of between 8 and 14 hours, and after at least 3 days of unrestricted diet (150 or more grams carbohydrate per day) and unlimited physical activity. The patient should remain seated and should not smoke throughout the test. Patient can have nothing by mouth except water during test period. GLUCOSE DOSE: Non-pregnant adults-50 grams.

Reference Range

Fasting 65-99

1 hour < 130