<prompt> Graves disease is the most common cause of-HypothyroidismHypehyroidismThyroiditisNone of the above  <response>: Graves disease is the most common cause of hypehyroidism 76 followed by Toxic multinodular goitre 14 and Toxic solitary thyroid adenoma 5. The thyrotoxicosis in Gravess disease results from the production of IgG antibodies directed against the TSH receptors on the thyroid follicular cells which stimulate thyroid hormone production and proliferation of follicular cells. These antibodies are known as thyroid stimulating immunoglobulins or TSH receptor antibodiesTRAb. Reference : page 740 and 747 Davidsons Principles and practice of Medicine 22nd edition 