1) Thyroid hormone 2) Triiodothyronine 1) Triiodothyronine 
(li″o-thi´ro-nēn) a synthetic pharmaceutical preparation of the levorotatory isomer of triiodothyronine; used for replacement therapy in hypothyroidism and for the prophylaxis and treatment of goiter and of thyroid cancer; administered orally or intravenously as the sodium salt.