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Test Code GTT5HR GTT GLU TOLERANCE, 5 HR HYPOGL

Performing Location

Southwestern Vermont Medical Center

Collection Instructions

Refer to Venipuncture Protocol and Standard Glucose Tolerance Protocols

 

Collection Container

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

Specimen Required/Volume

1.0 mL per each sample drawn

 

Specimen Type

serum

Turn-Around Guidelines

Upon arrival daily

Reference Values

Results Interpreted by Physician

 

Method

VITROS5600-Glucose Oxidase (Colorimetric)

CPT

Cpt code(s): 82951 + 82952

 

LOINC

50588-3

Special Handling

  1. Confirm that the 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 tolerance test.

  3. Draw fasting blood sample in green top tube or use hemmocue finger stick. Save 1 mL of serum frozen for possible insulin assay.

  4. Have patient drink 225 ml (7.5oz) of Dextol Glucose Tolerance Beverage for a dose of 75 grams of glucose. See dosage chart if patient weighs less than 91 lbs. Record time.

  5. Patient should be instructed to continue fasting with limited physical activity for the duration of the test. Monitor patient during test for symptoms of hypoglycemia.

  6. If symptoms appear, notify physician. Insulin and glucose levels determined at the time of symptoms are most diagnostic. Physician should determine whether to obtain sample at this time and/or continue test.

  7. Draw blood samples 1, 2, 3, 4 and 5 hours from the time the Dextol was given. Save 1 mL of serum from each specimen frozen for possible insulin assay.