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T4 Total

Test Code
THYROID TOTAL T4


Alias/See Also
T4, Thyroxine
Chemistry


Preferred Specimen
Gold Top Tube


Transport Temperature
Refrigerate


Specimen Stability
Refrigerated (2-8°C): 6 days
Frozen (-20°C or colder): 6 days
Avoid multiple freeze/thaw cycles


Methodology
Chemiluminescent microparticle immunoassay

Setup Schedule
M-F


Report Available
TAT 1 - 7 days


Reference Range
4.5 - 12.0 ug/dL


Clinical Significance
Thyroxine (T4) is the major secretory hormone of the thyroid. Only 0.03% of T4 is unbound and free for exchange with tissues. Thyroid function may be assessed with thyroid stimulating hormone (TSH) and free T4 measurements.


Performing Laboratory
Test performed at West Roxbury Chemistry Lab
Contact: Jonathan Dryjowicz-Burek 857-203-5973
 


Last Updated: November 20, 2025


The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.