Triiodothyronine, Free (Free T3)
Also known as: FT3
Use
The Triiodothyronine, Free (Free T3) test is used in the evaluation of thyroid function, specifically for assessing suspected thyroid disorders such as hyperthyroidism or in certain scenarios such as thyroid disease in pregnancy. Free T3 testing provides a measure of the metabolically active form of triiodothyronine, helping in the differentiation of various types of thyroid dysfunctions.
Special Instructions
Not recommended for routine thyroid screening; for initial thyroid disorder screening, refer to Thyroid Stimulating Hormone (0070145).
Limitations
Test results may be affected if the specimen is not separated from cells within 2 hours of collection. Grossly hemolyzed specimens will be rejected, which can lead to delays in diagnosis. Proper storage and handling conditions must be adhered to for accurate results, including collecting the specimen in a specified tube and transporting it refrigerated.
FDA ApprovedNew York Approved
Methodology
Immunoassay (ECLIA)
Biomarkers
LOINC Codes
- 3051-0
Result Turnaround Time
0-1 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
1 mL
Minimum Volume
0.5 mL
Container
Serum separator tube or plasma separator tube. Also acceptable: Lavender (K3EDTA or K2EDTA ), pink (K2EDTA), or green (lithium heparin)
Collection Instructions
Allow specimen to clot completely at room temperature. Separate serum or plasma from cells ASAP or within 2 hours of collection.
Storage Instructions
Refrigerated
Causes for Rejection
Grossly hemolyzed specimens
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 5 days |
| Refrigerated | 1 week |
| Frozen | 1 month |