Thyroid Stimulating Hormone with Reflex to Free Thyroxine
Also known as: TSHREFLEX
Use
This test is used to assess thyroid function and identify risk in individuals with palpable thyroid nodules. If the Thyroid Stimulating Hormone (TSH) level is outside of the reference range, a reflex test for Free Thyroxine (Free T4) is automatically conducted to provide more detailed thyroid analysis.
Special Instructions
The test includes a reflex to Free Thyroxine for thyroid stimulating hormone results outside the reference range. It's important to separate serum or plasma from cells as soon as possible or within 2 hours of collection to ensure specimen integrity.
Limitations
While the test provides a measure of TSH and reflexively Free T4 if indicated, factors such as sample handling, patient preparation, and the timing of specimen collection relative to thyroid hormone levels can affect results. Gross hemolysis may compromise the sample, making it unacceptable for testing.
New York Approved
Methodology
Immunoassay (ECLIA)
Biomarkers
LOINC Codes
- 3016-3
Result Turnaround Time
1 day
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
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 |
Other tests from different labs that may be relevant