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T4
Also known as: Total T4 and free T4
Formal name: Thyroxine
Related tests: TSH, T3, Thyroid Antibodies
Why get tested?
To help evaluate thyroid gland function; to help diagnose hypothyroidism or
hyperthyroidism; to screen for hypothyroidism in newborns.
When to get tested?
Usually ordering in response to an abnormal TSH test result or when a
patient has symptoms of hyper- or hypothyroidism; commonly performed on
newborns.
Sample required?
A blood sample drawn from a vein in the arm or from pricking the heel of an
infant.
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