Free triiodothyronine, or Free T3, is used to assess thyroid function and can either be used to diagnose hyperthyroidism or monitor treatment of a person with a known thyroid disorder.
Thyroid Stimulating Hormone (TSH)
The thyroid is a butterfly shaped gland found in the throat, wrapped around the windpipe just below the Adam’s apple. It produces thyroid hormones which influence essentially every organ, every tissue and every cell in the body. Thyroid Stimulating Hormone (TSH) is produced in the pituitary gland and stimulates the thyroid gland to produce thyroid hormones thyroxine (T4) and triiodothyronine (T3). TSH that is too high or too low indicates that your thyroid gland is not functioning correctly.
Free thyroxine helps to evaluate thyroid function and diagnose thyroid diseases, including hypo- and hyper-thyroidism. Free T4 is not affected by protein levels and is the active form of thyroxine.