T4 (Thyroxine), Total

Test Code

867

Alias/See Also

1230400528 | LAB126: T4 (Thyroxine), Total | QUEST EAP: 867 | THYROXINE|T4

CPT Codes
84436

Preferred Specimen

1 mL serum

Minimum Volume

0.5 mL

Other Acceptable Specimens

Plasma collected in: Sodium heparin (green-top) or lithium heparin (green-top) tube

Transport Container

Plastic screw-cap vial

Transport Temperature

Room temperature

Specimen Stability

Room temperature: 7 days
Refrigerated: 7 days
Frozen: 28 days

Methodology
Immunoassay (IA)

Setup Schedule

Set up: Daily; Report available: Next day

Limitations

Nonthyroidal chronic diseases, nicotinic acid and nutrition may decrease results. Thyrotoxicosis may not always cause abnormal results. Binding protein variations may cause variations in results. Increases may be associated with pregnancy or oral contraceptive use.

Reference Range

	Male (mcg/dL)	Female (mcg/dL)
<1 Month	4.5-17.2	4.5-17.2
1-23 Months	5.9-13.9	5.9-13.9
2-12 Years	5.7-11.6	5.7-11.6
13-20 Years	5.1-10.3	5.3-11.7
>20 Years	4.9-10.5	5.1-11.9

Clinical Significance

For diagnosis of hypothyroidism and hyperthyroidism.

Performing Laboratory
Quest Diagnostics Nichols Institute
14225 Newbrook Drive
Chantilly, VA 20153

Last Updated: April 21, 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.