Replacement therapy with levothyroxine plus triiodothyronine (bioavailable molar ratio 14:1) is not superior to thyroxine alone to improve well-being and cognitive performance in hypothyroidism. - Siegmund,W.; Spieker,K.; Weike,AI.; Giessmann,T.; Modess,C.; Dabers,T.; Kirsch,G.; Sanger,E.; Engel,G.; Hamm,AO.; Nauck,M.; Meng,W. (Clin Endocrinol (Oxf), 2004)