T4 free thyroid

T4 free (FT4, free T4, free T4, free thyroxine) is a thyroid hormone. This hormone ensures that all kinds of processes in the body run fast enough. A value that is too low indicates a thyroid that works too slowly. An FT4 reading that is too high indicates a thyroid that works too fast.

A lowered FT4 result fits hypothyroidism (slowed thyroid), thyreostatic therapy, iodine deficiency, autoimmune thyroiditis or during pregnancy.

Autoimmune thyroiditis is an autoimmune disease in which the body makes antibodies against its own thyroid gland and is the leading cause of underproduction of thyroid hormones in the Western world. The thyroid gland will inflame and be destroyed by the body's immune cells.

The disease is ten to twenty times more common in women than in men and is mainly seen in middle-aged women.