<prompt> A large toxic retrosternal goiter is best treated by-Antithyroid drugsRadio iodineSurgical resectionLugols iodine  <response>: Retrosternal goitre is most commonly defined as one that either descends below the thoracic inlet, or has more than 50 of its volume below this level. Surgery is the only effective treatment for retrosternal goitres. In most cases, suppressive therapy with thyroxine is ineffective in reducing the size of multinodular goitres ; radio-iodine therapy is both generally ineffective in large goitres and may induce acute inflammation and swelling of the gland with the potential for airway obstruction. Ref - 