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Test Code N.2HRGLU GLUCOSE TOLERANCE, 2 HR

Important Note

Not to be used for pregnant patients.

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. Patients can have nothing by mouth except water during test period.

GLUCOSE DOSE: Non-pregnant adults - 75 grams, children - 1.75 gm/kg of ideal body weight up to a maximum of 75 grams.

Each transfer tube must be clearly marked with time of draw.

Methodology

Automated Chemistry Analyzer

Specimen Requirements

Serum or Plasma

Container: SST tube or Lithium heparin plasma (green top tube)

Specimen Collection: 1 mL each specimen (minimum 0.5 mL each specimen)

  1. Draw fasting specimen just prior to 75 gram glucose load. Draw other specimen in 2 hours.
  2. Clearly label each specimen with time of draw.
  3. Allow specimen to clot completely if a serum (SST) was used for the draw.
  4. Separate serum (SST) or plasma (Lithium Heparin) from cells within 24 hours and transport refrigerated. If a red top tube is collected, separate serum from cells within 2 hours and place in separate plastic tube and cap immediately.
  5. Properly label specimen with patient's name, DOB, requisition number and type of tube drawn i.e. GREEN.

Alternate Specimens: Gray top (Sodium Fluoride)

Specimen Transport/Stability

Refrigerated: 24 hours on gel, 7 days poured off

Specimen Rejection

1.  Clotted specimen

2.  Exceeding stability requirements

3. Unlabeled specimen

Maximum Laboratory Time

24 - 48 hours

Reference Ranges

Glucose            mg/dL
Fasting         < 140
Impaired fasting glucose        100 - 125
Impaired glucose tolerance        140 - 199,  2 hours after 75 gm oral dose

Reference ranges based on the recommendations of the American Diabetes Association

 

 

Day(s) Test Set Up

Daily

Test Classification and CPT Coding

82950

82947