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HelpTest ID T3FR T3 (Triiodothyronine), Free, Serum
Specimen Required
Supplies: Sarstedt Aliquot Tube, 5 mL (T914)
Collection Container/Tube:
Preferred: Serum gel
Acceptable: Red top
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Collection Instructions: Centrifuge and aliquot serum into a plastic vial.
Reporting Name
T3 (Triiodothyronine), Free, SSpecimen Type
SerumSpecimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Serum | Refrigerated (preferred) | 14 days |
| Frozen | 30 days |
Report Available
1 to 3 daysPerforming Laboratory
Mayo Clinic Laboratories in Rochester
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| T3FR | T3 (Triiodothyronine), Free, S | 3051-0 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| T3FR | T3 (Triiodothyronine), Free, S | 3051-0 |
Useful For
A second- or third-level test of thyroid function
Confirmation of hyperthyroidism, supplementing the T4 (tetraiodothyronine), sensitive thyrotropin, and total T3 assays
Evaluating clinically euthyroid patients who have an altered distribution of binding proteins
Day(s) Performed
Monday through Saturday
Test Classification
This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.CPT Code Information
84481
Specimen Minimum Volume
0.75 mL
Reference Values
Pediatric
0-1 month: 2.7-8.5 pg/mL
1-<12 months: 3.4-5.6 pg/mL
1-<14 years: 3.0-5.1 pg/mL
14-<19 years: 3.3-5.3 pg/mL
Adult (≥19 years): 2.0-4.4 pg/mL
For International System of Units (SI) conversion for Reference Values, see www.mayocliniclabs.com/order-tests/si-unit-conversion.html.
Method Name
Electrochemiluminescence Immunoassay (ECLIA)