Free thyroxine (FT4)

Free thyroxine (FT4) is a hormone produced by the thyroid gland, which is located in your neck. It plays a vital role in controlling your body's metabolism, energy levels, and overall functioning. FT4 refers to the unbound, active form of thyroxine circulating in the blood, available to enter cells and influence various organs. Measuring FT4 helps doctors assess thyroid health, whether there is an underactive (hypothyroidism) or overactive (hyperthyroidism) thyroid. Maintaining appropriate FT4 levels is essential for normal growth, energy, and overall well-being.