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Specimen Collection Manual and Test Catalog

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GESTATIONAL GLUCOSE TOLERANCE, 3 HOUR

Geisinger Epic Procedure Code:  LAB3368    Geisinger Epic ID:  75072

SPECIMEN COLLECTION
Specimen type: 

Plasma


Preferred collection container: 
Specimen required: 

1 mL aliquot of plasma for each time interval; minimum 0.2 mL


Special notes: 

Specimens must be collected on a time schedule (FBS, 1-hour, 2-hour, and 3-hour). Place specimen on ice, or centrifuge and separate plasma from cells.


Patient preparation: 

8-hour fasting is required. 100-g glucose tolerating test for women at 24-28 weeks of gestation not previously diagnosed with diabetes.



SPECIMEN PROCESSING
Processing instructions: 

Centrifuge to separate plasma within 2 hours of collection.


Transport temperature: 

Refrigerated (preferred).


Specimen stability: 

3 days (spun and unspun).


Rejection criteria: 

Stability limits exceeded.



TEST DETAILS
Interpretation guide: 

Based on guidelines from American Diabetes Association, gestational diabetes diagnosis mellitus is made when at least two of the following are met: 
Fasting is greater than or equal to 95 mg/dL
1 hour is greater than or equal to 180 mg/dL 
2 hour is greater than or equal to 155 mg/dL 
3 hour is greater than or equal to 140 mg/dL 
 


Critical values/courtesy alerts: 
Glucose below 45, above 500 mg/dL
CPT code(s): 
Note: The billing party has sole responsibility for CPT coding.  Any questions regarding coding should be directed to the payer being billed.
The CPT codes provided by GML are based on AMA guidelines and are for informational purposes only.

Test includes: 

Fasting glucose (GEFAST), 1-hour glucose (GE10), 2-hour glucose (GE20) and 3-hour glucose (GE30)


Methodology: 
Spectrophotometric (Colorimetric)
Synonyms: 

Clinical significance: 

This test is used for the diagnosis of gestational diabetes.


Doctoral Director(s): 
Hoi-Ying Elsie Yu, PhD, DABCC, FADLM
Sheng-Ying (Margaret) Lo, PhD, DABCC
Review Date:  12/27/2024

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