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Test Name

T4 (Thyroxine), Total

To view specimen requirements and codes please Select a regional laboratory.

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CPT Code(s)**

84436
**IMPORTANT: CPT Code is informational only; obtain the Test Code for ordering.

Methodology

Immunoassay (IA)

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(s)

T4 (Thyroxine), Total  
  Male Female 
<1 Month 4.5-17.2 mcg/dL 4.5-17.2 mcg/dL
1-23 Months 5.9-13.9 mcg/dL 5.9-13.9 mcg/dL
2-12 Years 5.7-11.6 mcg/dL 5.7-11.6 mcg/dL
13-20 Years 5.1-10.3 mcg/dL 5.3-11.7 mcg/dL
>20 Years 4.9-10.5 mcg/dL 5.1-11.9 mcg/dL
     
Free T4 Index (T7) 1.4-3.8 1.4-3.8 

Clinical Significance

For diagnosis of hypothyroidism and hyperthyroidism.

Reference ranges are provided as general guidance only. To interpret test results use the reference range in the laboratory report.

The CPT codes provided 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 payer being billed.

* The tests listed by specialist are a select group of tests offered. For a complete list of Quest Diagnostics tests, please refer to our Directory of Services.

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867
T4 (Thyroxine), Total
867