Gestational Glucose Tolerance (Diagnostic)

Test ID: 

702956

CPT code:

82951, 82952

Synonyms:

Glucose Tolerance, Gestational Diabetes (Fasting, One-hour, Two-hour, and Three-hour)

Clinical Use:

Diagnose gestational diabetes

Specimen Type:

Serum or plasma

Requested Volume: 

1 mL serum or plasma each tube

Minimum Volume: 

0.5 mL

Container Type: 

Gel-barrier tubes (4) or gray-top (sodium fluoride/potassium oxalate plasma) tubes (4)

Patient Preparation: 

For three days prior to the test, patients should eat an unrestricted diet of 150 or more grams of carbohydrate and be permitted unrestricted physical activity. Patients should be instructed to eat and drink nothing except water for at least eight hours and not more than 14 hours before the test. Patients should also be advised to discontinue, whenever possible, all nonessential medication that can affect glucose metabolism at least three days before testing.

Collection:

Draw a fasting blood sugar before administering 100-gram glucose, and draw blood at one, two, and three hours. The subject should remain seated and not smoke throughout the test. Submit 1 mL serum or plasma for fasting, one-hour, two-hour, and three-hour specimens. Separate serum or plasma from cells within 45 minutes of venipuncture. Gray-top tubes only, may be submitted without centrifugation. Label each tube with patient’s name and collection time interval (ie, fasting, one-hour, two-hour, and three-hour).

Storage Instructions:

Maintain specimen at room temperature

Stability Requirements:

Rejection Criteria

Frozen gray-top tube (frozen plasma from gray-top is acceptable); stressed patient (surgery, infection, corticosteroids) should not have GTT; specimens not labeled with collection time intervals (i.e., fasting, one-hour, two-hour, and three-hour)