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HelpTest Code GTADA Glucose Tolerance - Fasting and 2HR
Useful For
The primary use of the oral glucose tolerance test is the diagnosis of diabetes mellitus.
The test measures the ability of the individual to remove an added glucose load from the circulation.
Blood samples are obtained at timed intervals after the ingestion of the test glucose load.
Synonyms/Keywords
Glucose Tolerance, Fast & 2Hr
Specimen Requirements
| Fasting Required | Specimen Type | Preferred Container/Tube | Acceptable Container/Tube | Specimen Volume | Specimen Minimum Volume (allows for 1 repeat) |
Pediatric Minimum Volume (no repeat) |
|---|---|---|---|---|---|---|
|
Yes 8 Hours |
Plasma/Serum | Lithium-heparin Plasma Separator (PST), Serum Separator Tube (SST) | Lithium or Sodium-heparin Green Top (GTT), Red Top Tube (RTT), Gray Top Tube (GYTT) | 1 mL | 0.3 mL |
Collection/Processing Instructions
**See Glucose Tolerance Guidelines for test protocol and interpretation.
Fluoride/oxalate is the preferred preservative if analysis is delayed more than one hour.
Usual Adult Glucose Test Dose = 75 g glucose.
The glucola must be consumed within a 5 minute interval; sipping water is permitted.
Patients should be ambulatory and on a high carbohydrate diet for at least 3 days prior to the test. Patient must be fasting for 8 hours prior to start of the tolerance test.
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Plasma/Serum | Ambient | 5 days |
| Refrigerate | 7 days |
Interpretations
American Diabetes Association Guidelines for the diagnosis of diabetes mellitus in non-pregnant patients are as follows (Diabetes Care Jan 2004, S5-S10):
Two separate days in which any two of the following events occur:
- fasting glucose ≥100 mg/dL or,
- random glucose ≥200 mg/dL or,
- 2 hour glucose following glucose load ≥200 mg/dL.
Reference Range Information
| Performing Location | Reference Range |
|---|---|
| All Performing Sites | See Interpretation |
Marshfield Labs Performing Department
Marshfield Labs Chemistry
Performing Information
| Performing Location | Day(s) Test Performed | Analytical Time | Methodology/Instrumentation |
|---|---|---|---|
| Chippewa Falls | Monday through Friday | Less than 2 hours | Hexokinase-UV/NAD Endpoint Assay/Beckman AU |
| Weston | Monday through Sunday | Less than 2 hours | Hexokinase-UV/NAD Endpoint Assay/Beckman AU |
| Eau Claire | Monday through Sunday | Less than 2 hours | Hexokinase-UV/NAD Endpoint Assay/Beckman AU |
| Park Falls | Monday through Sunday | Less than 2 hours | Hexokinase-UV/NAD Endpoint Assay/Beckman AU |
| Ladysmith | Monday through Sunday | Less than 2 hours | Hexokinase-UV/NAD Endpoint Assay/Beckman AU |
| Rice Lake | Monday through Sunday | Less than 2 hours | Hexokinase-UV/NAD Endpoint Assay/Beckman AU |
| Marshfield | Monday through Sunday | Less than 2 hours | Hexokinase-UV/NAD Endpoint Assay/Beckman AU |
| Minocqua | Monday through Sunday | Less than 2 hours | Hexokinase-UV/NAD Endpoint Assay/Beckman AU |
| Neillsville | Monday through Sunday | Less than 2 hours | Hexokinase-UV/NAD Endpoint Assay/Beckman AU |
| Stevens Point | Monday through Friday | Less than 2 hours | Hexokinase-UV/NAD Endpoint Assay/Beckman AU |
| Wisconsin Rapids | Monday through Friday | Less than 2 hours | Hexokinase-UV/NAD Endpoint Assay/Beckman AU |
CPT Codes
| CPT | Modifier (if needed) |
Quantity | Description | Comments |
|---|---|---|---|---|
| 82947 | Glucose | |||
| 82950 | Glucose, post dose |
Outreach CPT Codes
| CPT | Modifier (if needed) |
Quantity | Description | Comments |
|---|---|---|---|---|
| 82947 | Glucose | |||
| 82950 | Glucose, post dose |