Information on collection, storage, and volume
Serum or plasma
1 mL serum or plasma each tube
0.5 mL serum or plasma each tube
Gel-barrier tube or gray-top (sodium fluoride/potassium oxalate plasma) tube
Maintain specimen at room temperature.1
Frozen gray-top tube (frozen plasma from gray-top is acceptable); stressed patient (surgery, infection, corticosteroids) should not have GTT; specimen not labeled with collection time intervals (i.e., one hour)
Note: A fasting blood sample is not required. Draw one hour specimen after a 50-gram glucose challenge. The patient should remain seated and not smoke throughout the test. Submit 1 mL serum or plasma for one-hour specimen. Separate serum or plasma from cells within 45 minutes of venipuncture. Gray-top tubes only, may be submitted without centrifugation. Label tube with patient's name and collection time interval (ie, one-hour).