T4 TOTAL

Message

Centrifuge within 2 hours of collection.

Test Code

Alias/See Also

T4T;Syn-Thyroid;T4;T4 Total Only, T4, Serum;Tetraiodothyronine;Thyroid Hormone;Thyroxine (T4);Total T4

CPT Codes
84436

Preferred Specimen

1 Gold tube (gel separator)

Minimum Volume

0.2 mL

Other Acceptable Specimens

or 1 Green tube (Lithium Heparin)

Instructions

Centrifuge for complete separation of plasma or serum and red cells within 2 hours.

Transport Temperature

Refrigerate

Specimen Stability

2-8°C up to 7 days
15-30°C up to 8 hours
Frozen samples are stable

Methodology
Chemiluminescent immunoassay

Setup Schedule

M, T, W, Th, F, Sa, Sun

Reference Range

5.0 - 12.3 ug/dL

Clinical Significance

Total T4 aids in the diagnosis of hyper/hypothyroidism. In conjunction with TSH can determine if the feedback loop is intact. Includes both free and bound T4 and is affected by protein levels. Total thyroxine only provides correct information when the thyroxine-binding capacity in serum is normal.

Performed By
Alverno Laboratories

Performing Laboratory
Alverno Central Lab
NCHB2 (Chemistry, Beckman DxI)

Last Updated: April 25, 2023

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.