“+ noun
Etymology: tri- + iod- + thyronine
: a crystalline iodine-containing phenolic amino acid C 15 H 12 I 3 NO 4 that occurs in the levorotatory l -form in small amounts with thyroxine but is usually made synthetically, is believed to be formed from thyroxine by loss of one iodine atom per molecule, has a more rapid and potent but briefer physiological action than thyroxine, and is used especially in the form of its soluble sodium salt in the treatment of hypothyroidism and metabolic insufficiency