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Geisinger Medical Laboratories Test Catalog
GLUCOSE TOLERANCE TEST, 2 HOUR |
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ORDERING INFORMATION: |
Geisinger Epic Procedure Code: LAB3784 Geisinger Epic ID: 142590 | |
SPECIMEN COLLECTION |
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Specimen type: |
Plasma | |
Preferred collection container: |
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Specimen required: |
1 mL aliquot of plasma for each time interval; minimum 0.2 mL for each time interval. | |
Special notes: |
Specimens must be collected on a time schedule (fasting and 2 hour). Place specimen on ice, or centrifuge and separate plasma from cells. | |
Patient preparation: |
8-hour fasting is required. After collection of fasting specimen, 75 g of glucose should be given immediately for adult. For children (under 18 years of age), 1.75 g glucose/kg ideal body weight up to a maximum dose of 75 g or per physician request. | |
| SPECIMEN PROCESSING |
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Specimen 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 |
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Interpretation guide: |
Fasting plasma glucose: Normal 70-99 mg/dL, impaired tolerance 100-125 mg/dL, abnormal diabetic > or = 126 mg/dL. 2-hour post challenge: Normal 90-139 mg/dL, impaired tolerance 140-199 mg/dL, abnormal diabetic > or = 200 mg/dL. Diabetes diagnosis requires two abnormal diabetes diagnostic test results |
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Critical values/courtesy alerts: |
Glucose below 45, above 500 mg/dL. | |
CPT code(s): |
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| 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: |
Glucose, fasting plasma, and glucose, 2-hour post challenge. | |
Methodology: |
Spectrophotometric (Colorimetric) |
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Synonyms: |
OGTT, PCG
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Clinical significance: |
This test is used for the diagnosis of diabetes. | |
Doctoral Director(s:) |
Hoi-Ying Elsie Yu, PhD, DABCC Sheng-Ying (Margaret) Lo, PhD, DABCC |
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| Review Date: | 12/14/2022 | |
Performing Locations
Geisinger Wyoming Valley Medical Center