Reverse T3
Also known as: T3, Reverse
Use
Reverse triiodothyronine (rT3) is an isomer of triiodothyronine (T3) with no demonstrated biological activity. The majority of rT3 is produced through peripheral enzymatic monodeiodination of T4 at the 5 position of the inner ring of the iodothyronine nucleus of thyroxine (T4). A lesser amount is secreted directly by the thyroid gland. rT3 is biologically inactive and does not stimulate thyroid hormone receptors. In nonthyroidal illness syndrome, rT3 levels increase while T3 levels decrease, seen in acute or chronic systemic nonthyroidal illnesses. An elevated rT3 level can independently predict increased mortality in acutely ill patients.
Special Instructions
Not provided.
Limitations
This test was developed and its performance characteristics determined by LabCorp. It has not been cleared or approved by the Food and Drug Administration. The conversion of T4 to rT3 is increased in illness due to increased 5'-deiodinase activity. Significant changes in rT3 occur rapidly in acute illness with maximal changes 24-36 hours post-symptom onset.
Methodology
Mass Spectrometry
Biomarkers
Reverse T3
Analyte
LOINC Codes
- 3052-8 - T3Reverse SerPl-mCnc
- 3052-8 - T3Reverse SerPl-mCnc
Result Turnaround Time
4-6 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
1.2 mL
Minimum Volume
0.8 mL
Container
Red-top tube or gel-barrier tube
Collection Instructions
If a tube other than a gel-barrier tube is used, transfer separated serum to a plastic transport tube.
Storage Instructions
Room temperature
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 14 days |
| Refrigerated | 14 days |
| Frozen | 14 days |
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