Monoiodotyrosine (MIT) is an iodinated derivative of the amino acid tyrosine. It is an important intermediate in the biosynthesis of thyroid hormones. In the thyroid gland, iodination of tyrosine residues within the thyroglobulin molecule produces MIT, which subsequently participates in the formation of thyroid hormones such as thyroxine (T4) and triiodothyronine (T3).