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22660 Glucose Tolerance

Glucose Tolerance
Test Code: GTT-HR
Synonyms/Keywords
​Glucose Tolerance - 2 hr, 3 hr
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.​
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 (RTT),Gray Top (GYTT) 1 mL​ 0.3 mL​ ​
Collection Processing Instructions

**See Glucose Tolerance Tests.pdf 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​
Performing Laboratory Information
Performing Location Day(s) Test Performed Analytical Time Methodology/Instrumentation
Chippewa Falls​ ​Monday through Friday ​2-4 hours ​​Modified Hexokinase Method/Siemens Dimension
Weston​ ​​Monday through Friday ​4-6 hours ​Modified Hexokinase Method/Siemens Dimension
Eau Claire​ ​Monday through Sunday​ ​4-6 hours ​​Hexokinase-UV/NAD Endpoint Assay/ Beckman AU
Park Falls
 ​​Monday through Friday ​​4-6 hours Hexokinase-UV/NAD Endpoint Assay/ Beckman AU
Ladysmith​ ​Monday through Friday ​​2-4 hours Hexokinase-UV/NAD Endpoint Assay/ Beckman AU​
​Lakeview Medical Center ​Monday through Sunday ​​​4-6 hours Hexokinase-UV/NAD Endpoint Assay/ Beckman AU
Marshfield​ Monday through Sunday​ ​​4-6 hours Hexokinas-UV/NAD Endpoint Assay/Beckman AU
​Minocqua ​Monday through Sunday​ ​​​4-6 hours ​​Hexokinase-UV/NAD Endpoint Assay/ Beckman AU
Neillsville​​Monday through Sunday​​​​4-6 hoursModified Hexokinase Method/Siemens Dimension​
Stevens Point​ Monday through Friday​ ​​​4-6 hours​ ​Hexokinas-UV/NAD Endpoint Assay/Beckman AU
​Wisconsin Rapids ​Monday through Friday ​​​2-4 hours ​​Modified Hexokinase Method/Siemens Dimension
Test Information

 

​Performing Location Glucose Tolerance Test Offered​
Chippewa Falls​     2-hr, 3-hr
Weston
     ​​2-hr, 3-hr
Eau Claire​     ​2-hr, 3-hr
Park Falls​​     ​​2-hr, 3-hr
​Ladysmith     ​2-hr, 3-hr
​Lake Hallie     ​2-hr, 3-hr
​Lakeview Medical Center     ​2-hr, 3-hr
​Marshfield ​    2-hr, 3-hr
​Minocqua
     ​2-hr, 3-hr
​Neillsville​    ​2-hr, 3-hr
Stevens Point​ ​    2-hr, 3-hr
​Wisconsin Rapids ​​    2-hr, 3-hr
 
Reference Range Information
Performing Location Reference Range
All Performing Sites See Interpretation​
Interpretation
American Diabetes Association Guidelines for the diagnosis of diabetes mellitus in non-pregnant patients are as follows:
Two separate days in which any two of the following events occur:
fasting glucose >= 126 mg/dL or,
random glucose >=200 mg/dL or,
2 hr glucose following glucose load >=200 mg/dL​
Outreach CPTs
CPT Modifier
(if needed)		 Quantity Description Comments
82951 ​ ​ ​  Up to 3 specimens ​ ​
82952​ ​ ​  Each additional specimen​ ​
Synonyms/Keywords
​Glucose Tolerance - 2 hr, 3 hr
Ordering Applications
Ordering Application Description
If the ordering application you are looking for is not listed, contact your local laboratory for assistance.
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 (RTT),Gray Top (GYTT) 1 mL​ 0.3 mL​ ​
Collection Processing

**See Glucose Tolerance Tests.pdf 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​
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.​
Reference Range Information
Performing Location Reference Range
All Performing Sites See Interpretation​
Interpretation
American Diabetes Association Guidelines for the diagnosis of diabetes mellitus in non-pregnant patients are as follows:
Two separate days in which any two of the following events occur:
fasting glucose >= 126 mg/dL or,
random glucose >=200 mg/dL or,
2 hr glucose following glucose load >=200 mg/dL​
For more information visit:
Performing Laboratory Information
Performing Location Day(s) Test Performed Analytical Time Methodology/Instrumentation
Chippewa Falls​ ​Monday through Friday ​2-4 hours ​​Modified Hexokinase Method/Siemens Dimension
Weston​ ​​Monday through Friday ​4-6 hours ​Modified Hexokinase Method/Siemens Dimension
Eau Claire​ ​Monday through Sunday​ ​4-6 hours ​​Hexokinase-UV/NAD Endpoint Assay/ Beckman AU
Park Falls
 ​​Monday through Friday ​​4-6 hours Hexokinase-UV/NAD Endpoint Assay/ Beckman AU
Ladysmith​ ​Monday through Friday ​​2-4 hours Hexokinase-UV/NAD Endpoint Assay/ Beckman AU​
​Lakeview Medical Center ​Monday through Sunday ​​​4-6 hours Hexokinase-UV/NAD Endpoint Assay/ Beckman AU
Marshfield​ Monday through Sunday​ ​​4-6 hours Hexokinas-UV/NAD Endpoint Assay/Beckman AU
​Minocqua ​Monday through Sunday​ ​​​4-6 hours ​​Hexokinase-UV/NAD Endpoint Assay/ Beckman AU
Neillsville​​Monday through Sunday​​​​4-6 hoursModified Hexokinase Method/Siemens Dimension​
Stevens Point​ Monday through Friday​ ​​​4-6 hours​ ​Hexokinas-UV/NAD Endpoint Assay/Beckman AU
​Wisconsin Rapids ​Monday through Friday ​​​2-4 hours ​​Modified Hexokinase Method/Siemens Dimension
For billing questions, see Contacts
Outreach CPTs
CPT Modifier
(if needed)		 Quantity Description Comments
82951 ​ ​ ​  Up to 3 specimens ​ ​
82952​ ​ ​  Each additional specimen​ ​
For most current information refer to the Marshfield Laboratory online reference manual.