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 #

T4 (Thyroxine), Total

Test Code
T4


Quest Code
867


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


Instructions
Note: Free T4 Index (T7) will only be calculated and reported if test code code 861 (T3 Uptake) is ordered as well.


Transport Container
Serum separator tube (SST)


Transport Temperature
Room temperature


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


Methodology
Immunoassay (IA)

Setup Schedule
Daily


Report Available
1 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 Month4.5-17.24.5-17.2
1-23 Months5.9-13.95.9-13.9
2-12 Years5.7-11.65.7-11.6
13-20 Years5.1-10.35.3-11.7
>20 Years4.9-10.55.1-11.9


Clinical Significance
For diagnosis of hypothyroidism and hyperthyroidism.


Performing Laboratory
Quest Diagnostics-Lenexa
10101 Renner Blvd
Lenexa , KS 66219-9752



Last Updated: February 19, 2024


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.