Thyroxine-Binding Protein Electrophoresis, Serum
Use
This test is useful for explaining unusual thyroxine (T4), free T4, and thyroxine-binding globulin test results that do not correlate with the patient's clinical presentation. It is also helpful in detecting the presence of aberrant thyroxine-binding proteins, such as abnormal forms of albumin and prealbumin, and detecting selective deficiency of one of the thyroxine-binding proteins. Additionally, it can detect antibodies to T4 and serve as an adjunct in diagnosing patients with high T4 concentration due to peripheral hormone resistance by ruling out thyroxine-binding abnormalities.
Special Instructions
This test should not be requested in patients who have recently received radioisotopes, therapeutically or diagnostically, due to potential assay interference. The recommended time period before collection depends on the isotope administered, the dose given, and the clearance rate in the individual patient. Total thyroxine (T4) test should not be used in patients receiving treatment with lipid-lowering agents containing dextrothyroxine unless therapy is discontinued for 4 to 6 weeks to allow the T4 physiological state to become re-established prior to testing.
Limitations
Thyroxine-binding globulin values may be elevated in women taking estrogens and during pregnancy. In rare cases, interference from human anti-mouse antibodies or heterophile antibodies can occur in some immunoassays. Caution is advised in interpreting results that do not correlate with the clinical presentation, and the laboratory should be alerted if such discrepancies occur. The assay is also sensitive to interference from recent radioisotope administration.
New York Approved
Methodology
Other (Electrophoresis)
Biomarkers
LOINC Codes
- 48073-1
- 83119-8
- 14016-0
- 11062-7
- 14014-5
- 48767-8
- 50681-6
Result Turnaround Time
29-35 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
1.6 mL
Minimum Volume
0.8 mL
Container
Plastic vial
Collection Instructions
Centrifuge and aliquot serum into a plastic vial.
Patient Preparation
For 12 hours before specimen collection, patient should not take multivitamins or dietary supplements containing biotin (vitamin B7).
Causes for Rejection
Gross hemolysis, Gross lipemia, Gross icterus
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 24 hours |
| Refrigerated | 7 days |
| Frozen | 30 days |