Free T4 Thyroxine Normal. The normal level of free thyroxine in the body of an adult is 0.8 to 2.8 nanograms per deciliter (ng/dl). This test has few different names like free thyroxine or thyroxine screen, total t4 concentration, and free t4 or free t4 concentration.
By seeing if you are in the normal range, the free t4 test can help detect. The normal level of free thyroxine in the body of an adult is 0.8 to 2.8 nanograms per deciliter (ng/dl). T4 hormone (thyroxine) is produced by the thyroid gland, placed near the neck, along with the t3 hormone (triiodothyronine).
Total t4 depends on thyroid binding globulins and may be elevated in pregnancy, contraceptive pill intake etc.
A free t4 measures what is not bound and able to enter and affect the body tissues. A level of free t 4 that is higher than normal could mean you have an overactive thyroid. While total t4 is a relatively reliable indicator of t4 levels in the presence of normal binding proteins, it is not a reliable indicator when binding proteins are abnormal. And this correlates well with newer studies which show that patients with hypothyroidism require a higher free t4 to achieve a normal tsh (1).
