Thyroid hormone

'Thyroid Hormone' is an umbrella term referring to Triiodothyronine, T₃, and Thyroxine, T₄, two Tyrosine-based hormones produced by the Thyroid gland. Their synthesis involves the iodination of two precursors, monoiodothyronine, T_1, and Diiodothyronine, T_2. Although Thyroxine is produced in larger quantities, it must be noted that Triiodothyronine is three to eight times more active. Thus, Thyroxine is metabolised into Triiodothyronine for active use. The thyroid hormones are involved in growth, working synergistically with Growth hormone, in cellular metabolism and in bodily Thermogenisis.

The level of thyroid hormones carried in the blood plasma must be regulated; an increase in the level of thyroid hormone activity