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Unit Code 8725:
T4 (Thyroxine), Free, Serum

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Useful For

The test generally is used as a second-line test after thyroid-

stimulating hormone (TSH) to help evaluate TSH changes

 

The FT4 value, combined with the TSH value, gives a more accurate

picture of the thyroid status in patients with abnormal thyroid-binding
globulin (TBG) levels such as those who are pregnant or those who
are receiving treatment with estrogens, androgens, phenytoin, or
salicylates.

Special Instructions and Forms

• Thyroid Function Algorithm 

Method Name

Chemiluminometric Immunoassay
See "Thyroid Function Algorithm" in Special Instructions.

Reporting Name

T4 (Thyroxine), Free, S

Ordering Mnemonic

FT4

Aliases

Free T4 (Thyroxine)

Free Thyroxine

Non-Protein Bound Tetraiodothyronine

Thyroid Function Cascade  ORDER 80683

Thyroxine, Free

Key