Triiodothyronine, Total and Triiodothyronine, Reverse with Ratio Calculation by Tandem Mass Spectrometry
Also known as: T3RT3RATIO
Use
The test measures total Triiodothyronine (T3) and reverse Triiodothyronine (rT3) levels in the blood, which are important for assessing thyroid function. This combined measurement assists clinicians in diagnosing and managing disorders related to thyroid hormone metabolism, such as hypothyroidism and various forms of thyroiditis. The ratio of T3 to rT3 can provide additional insights into metabolic activity and is particularly useful in differentiating between conditions that cause changes in thyroid hormone levels.
Special Instructions
Specimens require careful handling to ensure accurate results. Serum or plasma must be promptly separated from cells and properly stored to maintain specimen integrity. Use of appropriate transport tubes is necessary for compatibility with the laboratory's testing protocols.
Limitations
The assay uses tandem mass spectrometry which is sensitive to interference by hemolysis and may not correctly measure analyte levels in grossly hemolyzed specimens. This test was developed as a laboratory-developed test (LDT) and is not FDA-approved; not all clinical situations are validated. Results should be interpreted by a qualified clinician in conjunction with clinical findings.
New York Approved
Methodology
Mass Spectrometry
Biomarkers
LOINC Codes
- 3052-8
- 3053-6
- 57899-7
Result Turnaround Time
1-5 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
2 mL
Minimum Volume
1 mL
Container
ARUP Standard Transport Tube
Collection Instructions
Allow serum specimen to clot completely at room temperature. Separate serum or plasma from cells ASAP or within two hours of collection.
Storage Instructions
Frozen
Causes for Rejection
Grossly hemolyzed specimens.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 24 hours |
| Refrigerated | 1 week |
| Frozen | 3 months |