Thyroxine Binding Globulin
Also known as: TBG
Use
Thyroxine Binding Globulin (TBG) is a protein that binds thyroid hormones in the bloodstream. Measuring TBG levels can assist in the diagnosis and management of thyroid disorders, including conditions like hypothyroidism and hyperthyroidism. Evaluating TBG can help differentiate between thyroid-related and non-thyroid-related causes of abnormal thyroid function test results. However, it is not recommended for routine thyroid screening.
Special Instructions
This test is not recommended for routine thyroid screening and is New York state approved. It should be ordered using an ARUP Standard Transport Tube for the serum sample. Ensure proper labeling and submission to avoid rejection due to unacceptable conditions such as plasma or tissue submissions.
Limitations
This test cannot distinguish between free and bound thyroxine or assess thyroid function directly. Grossly hemolyzed or lipemic samples may affect the accuracy of the results. Results can be influenced by factors such as medications, pregnancy, and other binding protein abnormalities, which may complicate interpretation in certain clinical contexts.
New York Approved
Methodology
Immunoassay (CLIA)
Biomarkers
LOINC Codes
- 3021-3
Result Turnaround Time
1-4 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
0.5 mL
Minimum Volume
0.4 mL
Container
ARUP Standard Transport Tube
Collection Instructions
Collect blood in a serum separator tube and transfer to the ARUP transport tube.
Storage Instructions
Store and transport the specimen frozen.
Causes for Rejection
Plasma, tissue or urine specimens; grossly hemolyzed or lipemic specimens.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 24 hours |
| Refrigerated | 1 week |
| Frozen | 1 month |