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HELPFUL LINKS!

 

LAB COMMUNICATIONS 

 

COLLECTION & HANDLING

 

SPECIMEN TRANSPORTATION

Please call 616.774.7721 for specimen pick up

 

GENERAL INFORMATION

 

GENERAL TEST INFORMATION

 

BILLING

 

WEBSITES

Mayo Clinic Laboratories

Epic Code LAB1230102 Glucose Tolerance, 2 hour test, 75g (Non-Gestational)

Important Note

  • This test is recommended and only available for non=pregnant patients.
  • Fasting specimen required -  A fasting glucose specimen will be drawn.

Test Name Alias

Glucose tolerance 2 hr Test (Lab only) Glucose | 2 hr, Glucose Tolerance | Glucose | O9221  | GTT | OGTT | 178

Interface Order Alias

1230102

Ordering Instructions

  • This test is recommended and only available for NON-PREGNANT patients.
  • The patient must be fasting for this test. No caloric or caffeine intake for at least 8 hours. Do not drink (other than water), eat, smoke, chew gum, candy, cough drops, etc. for at least 8 hours prior to blood tests.
  • For safety and accuracy of testing, patients are encouraged to have Oral Glucose Tolerance Tests (OGTT) performed at one of our Outpatient Service Centers.
  • GlucoCrushTM, the glucola drink used in Spectrum Health Grand Rapids Laboratory does not contain gluten.

Collection Instructions

  • A fasting glucose specimen will be drawn.
  • The patient is given a 75 gram oral glucose load.
    • Pediatric patients under 95 lbs: Use the following calculation to determine the amount of glucola to be administered: 2.4 x Body weight in lbs = mL of 100g Glucola to administer
  • A second specimen is drawn two hours later.
  • GlucoCrushTM, the glucola drink used in Spectrum Health Grand Rapids Laboratory does not contain gluten.

 

Specimen Collection: Blood

 

Container(s): 4.5 mL Mint Green Top (Lithium Heparin Gel) or 5.0 mL Gold Top (Serum Separator-SST Gel)

  • Preferred Volume to Collect: 4.5 mL
  • Minimum Volume to Collect: 1.0 mL
  • Neonate Volume to Collect: 0.5 mL
  • Capillary collect ok? Yes
  • Microtainer acceptable: Yes

 

 

Collection Instructions:

  • Fasting specimen required
  • After collection, gently invert tube 8-10 times.
  • Specimen should be processed within 2 hours – See Processing Instructions.

 

Processing Instructions (Laboratory, Outpatient or Off-site collection)

  • Processed Specimen: Plasma or Serum
  • Centrifuge/Spin: Yes
  • Aliquot: Yes
  • Processing Instructions:
    • Plasma is preferred specimen type
    • Green Tube/Plasma: Centrifuge after collection.
    • Gold Tube/Serum: Allow blood to clot for 30 minutes in a vertical position and centrifuge within 2 hours.
    • Minimum plasma/serum volume: 0.5 mL
  • Transport Temperature: Refrigerate

Specimen Stability

Ambient: 8 hours

Refrigerate: 72 hours

Frozen: aliquot plasma/serum for longer storage

Laboratory Retention: 72 hours

Test Frequency

Available daily, usual TAT 1 day.

Reference Range

  Fasting 2 hour
Normal 70 - 99 mg/dL 65 - 139 mg/dL
Prediabetes 100 - 125 mg/dL 140 - 199 mg/dL
Diabetes ≥126 mg/dL ≥ 200 mg/dL

 

Diagnosis of diabetes requires 2 abnormal test results from the same sample type or in 2 separate test samples.

Classification and Diagnosis of Diabetes: Standards of Medical Care in Diabetes - 2021. Diabetes Care Jan; 44(Supplement 1):S15-S33.  https://doi.org/10.2337/dc21-S002 

Performing Department

Chemistry

Performing Department Laboratory Location

CHW: Corewell Health Reference Laboratory, Grand Rapids, MI
CHS: Corewell Health Lakeland St. Joseph Laboratory, St. Joseph, MI

Methodology

Enzymatic

CPT

82951, 82947

CDM Code

3018294701, 3018294701

Epic Test ID

1230100114, 1230100723

LOINC

Currently not available

Reviewed Date

3/7/2024

Updated Date

3/14/2024 - Reference Range

5/13/2025 - CHS info added