A B C D E F G H I J K L M N O P Q R S T U V W X Y Z #

T3, Free

Message
Performing Lab: Central Lab, Regions


Test Code
3803


Alias/See Also
Sunquest: T3FRE; Triiodothyronine, Free


CPT Codes
84481

Preferred Specimen
0.3 mL Lithium Heparin Plasma (light green-top) tube


Minimum Volume
0.25 mL


Other Acceptable Specimens
Serum (gold-top) tube


Instructions
Centrifuge specimens and remove the serum or plasma from the cellular material within 2 hours of collection.


Transport Temperature
Refrigerated


Specimen Stability
Room Temperature: 24 hours
Refrigerated: 6 days
Frozen: 6 days


Methodology
Chemiluminescent microparticle immunoassay (CMIA)

Setup Schedule
Monday - Friday


Report Available
Same Day


Reference Range
1.7 - 3.7 pg/mL


Clinical Significance
The free fraction of the circulating triiodothyronine (T3) is considered to exert the main influence on metabolic control. In hyperthyroidism, FT3 concentrations are generally elevated and give efficient discrimination at the euthyroid/toxic borderline, providing an effective method for confirming hyperthyroidism and monitoring of its treatment. In hypothyroidism, FT3 concentrations tend to be lower, but the decrease is insufficient to give clear diagnostic information. FT3 concentrations are independent of the concentration of thyroid hormone-binding proteins, and may be measured in patients with elevated or reduced binding protein concentrations without the need for additional tests of binding capacity. FT3 determinations should be used as part of a thyroid test strategy, which may include free T4 and high sensitivity TSH tests.




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.