T3 (TRIIODOTHYRONINE) FREE

Test Code

LAB137

CPT Codes
84481

Preferred Specimen

One 4.5 mL, Light Green top tube

Minimum Volume

2mL blood
1mL serum

Other Acceptable Specimens

Gold top tube
Red top tube
Dark Green Top tube

Instructions

Sample must be centrifuged within two hours of collection. Serum must be removed from red cells and put into aliquot tubes following centrifugation.

Transport Temperature

Refrigerated

Specimen Stability

Ambient: 24 hours
Refrigerated: 6 days
Frozen: 6 days

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)

Tubid, lipemic, grossly hemolyzed or heat-inactivated specimens

Methodology
Chemiluminescent Microparticle Immunoassay

Setup Schedule

Sunday-Saturday

Reference Range

Age	Reference values
0D-12M	2.3-4.9 pg/mL
1Y-11Y	2.8-4.4 pg/mL
12Y-14Y	2.5-4.1 pg/mL
15Y-18Y	2.3-3.8 pg/mL
>=19Y	1.7-3.7 pg/mL

Clinical Significance

Free T3 is a preferred secondary indicator of thyroid status because it reflects active T3 levels and is not sensitive to changes in thyroid
binding globulin or other blood proteins whose levels can be altered in disease and as a result of drug therapies.

Performing Laboratory
West Virginia University Hospital, Inc.
Berkeley Medical Center
Camden Clark Medical Center
St. Joseph’s Hospital
United Hospital Center
Uniontown Hospital
Wheeling Hospital

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.