Synonyms: T3; T3 Hormone; T3, Total; Total T3 Why It Is Done • Evaluate thyroid funtion • Screen for hypothyroidism • Screen for hyperthyroidism Test Overivew: Most of the T3 in the blood is attached to the thyroxine-binding globulin. Less than 1% of the T3 is unattached. A T3 blood test measure can measure both bound and free triiodothyronine. T3 has a greater effect on the way the body uses energy than T4, even though T3 is normally present in smaller amounts than T4. How to Prepare: No special preparation required |