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T4, (Thyroxine)

Test Code
T4


Preferred Specimen
Serum, 0.1 mL minimum


Transport Container
SST tube


Transport Temperature
Specimen stable for 8 hours at room temp., 2 days refrigerated and >2 days frozen.


Reference Range
See report for normal ranges.


Clinical Significance
Secreted into circulation in response to the TSH. Elevated T4 levels are seen in hyperthyroidism and acute thyroiditis. Low levels of T4 are seen in hypothyroidism, myxedema, cretinism, chronic thyroiditis and sub-acute thyroiditis.




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.