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Test Code GTT3HR GTT GLU TOLERANCE, 3HR PREG

Performing Location

Southwestern Vermont Medical Center

Collection Instructions

Refer to Venipuncture Protocol and Standard Glucose Tolerance Protocols

 

Collection Container

Green top for fasting drawn, gold top for every draw after.

Specimen Required/Volume

1.0 mL each specimen

 

Specimen Type

serum

Turn-Around Guidelines

Daily upon arrival

Reference Values

INTERPRETATION OF 3 HR GESTATIONAL GTT:

Criteria for diagnosis of gestational Diabetes Mellitis:

Any two patient levels above the following cutoff levels. (100 gm challenge)

Fasting: 95 mg/dL

1 hour: 180 mg/dL

2 hour: 155 mg/dL

3 hour: 140 mg/dL

 

DIABETES CARE; JANUARY 2001, p. S78

 

Method

VITROS5600-Glucose Oxidase (Colorimetric)

CPT

82951

LOINC

50608-9

Special Handling

  1. Confirm that patient has fasted 10-16 hours.

  2. Collect urine sample and run dipstick urine test. If test is positive consult physician to determine whether to continue with a tolerance test.

  3. Draw fasting blood sample.

  4. Have patient drink 300ml (10oz) of Dextol Glucose Tolerance Beverage for a dose of 100 grams of glucose. Record time.

  5. Patient should be instructed to remain seated, continue fasting and not to smoke during the test. Ask patient to notify staff if she should feel ill.

  6. Draw blood samples at 1, 2 and 3 hours from the time the Dextol was given.