Template:POTD/2023-05-26
Thyroid hormones are hormones produced and released by the thyroid gland, namely triiodothyronine (T3) and thyroxine (T4). They are tyrosine-based hormones that are primarily responsible for regulation of metabolism. T3 and T4 are partially composed of iodine, derived from food. A deficiency of iodine leads to decreased production of T3 and T4, enlarges the thyroid tissue and will cause the disease known as simple goitre. This illustration shows the synthesis of thyroid hormones, as seen on an individual thyroid follicular cell.Illustration credit: Mikael Häggström