Also known as: FT3; Triiodothyronine
Formal name: Free Triiodothyronine; Total Triiodothyronine
At a Glance
Why Get Tested?
To help evaluate thyroid gland function; to diagnose thyroid disease, including hyperthyroidism, and determine the cause; to monitor effectiveness of treatment of a thyroid disorder
When to Get Tested?
When you have an abnormal TSH, particularly with a normal free T4 result, and/or signs and symptoms of hyperthyroidism
A blood sample taken from a vein in your arm
Test Preparation Needed?
None needed; however, certain medications can interfere with the free T3 and total T3 tests, so tell your health practitioner about any drugs that you are taking.