Thyroxine (T4), Free, Dialysis/Mass Spectrometry (Endocrine Sciences)
Also known as: Free Thyroxine (T4) by Dialysis/Mass Spectrometry
Use
This test measures the free fraction of Thyroxine (T4) in the blood, which is the portion not bound to proteins in the blood. Free T4 is a crucial hormone for proper metabolism regulation and is an essential indicator of thyroid function. It helps in diagnosing and monitoring thyroid disorders such as hypothyroidism and hyperthyroidism, guiding appropriate clinical interventions.
Special Instructions
For accurate results, ensure serum or plasma is separated from cells within 45 minutes of venipuncture. To avoid delays in turnaround when multiple tests are requested on frozen samples, submit separate frozen specimens for each test.
Limitations
The test may not reflect changes in thyroid function rapidly due to physiological variations. Variations in serum protein binding can influence the levels of total thyroxine but not free thyroxine, thus free T4 is considered a more reliable indicator of thyroid function. However, interfering substances in the serum, variation in dialysis technique, and patient non-compliance in specimen handling may affect accuracy and reliability of the results.
Methodology
Mass Spectrometry
Biomarkers
LOINC Codes
- 6892-4
- 6892-4
Result Turnaround Time
6-11 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
1 mL
Minimum Volume
0.5 mL
Container
Red-top tube, gel-barrier tube, or lavender-top (EDTA) tube
Collection Instructions
Serum or plasma must be separated from cells within 45 minutes of venipuncture. Send serum or plasma in plastic transport tube.
Storage Instructions
Freeze
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 2 days |
| Refrigerated | 5 days |
| Frozen | 453 days |