Synonyms: T4, Total; Tetraiodothyronine
Why It Is Done
This test is used to evaluate thyroid function and screen for hyperthyroidism or hypothyroidism. Shows effectiveness of medications to treat thyroid disease. Used to diagnose T4 toxicosis.
Test Overview
Total thyroxine (T4). Thyroxine is a hormone produced by the thyroid and is responsible for your metabolism. .Most of the thyroxine (T4) in the blood is attached to a protein called the thyroxine-binding globulin. Less than 1% of the T4 is unattached. A total T4 blood test measures both bound and free thyroxine. Free thyroxine affects tissue function in the body, but bound thyroxine does not
How To Prepare
No special preparation required