Thyroid hormones and antithyroid drugs Shi-Hong Zhang ( ) Front view Thyroid gland Biosynthesis of thyroid hormones 1. Uptake of iodide 2. Oxidation of iodide (peroxidase) and iodination and coupling of tyrosine 3. Formation of thyroxine (T 4 ) and triiodothyronine (T 3 ) from iodotyrosine (peroxidase) 4. Secretion of thyroid hormones (proteolytic enzymes) 5. Regulation by thyroid stimulating hormone (TSH), T 4, T 3 1 2 3 Hypothyroidism cretinism ( ) simple goiter ( ) Hypothyroidism After treatment Hyperthyroidism Hypothyroidism: iodine and iodides ( small doses); thyroid hormone Therapeutic drugs on thyroid dysfunction 1 2 3 T 3 T 3 50%