Thyroxine, commonly referred to as T4, is a vital hormone produced by the thyroid gland. It plays a crucial role in regulating metabolism, growth, and development in the human body. T4 is one of the two major hormones synthesized by the thyroid, the other being triiodothyronine (T3). In the bloodstream, T4 is mostly bound to proteins and acts as a precursor to T3, the more active form of the hormone.
