a 43-year-old woman presents with palpitations. vital signs are bp 135/90 mm hg, hr 115 bpm, and rr 16/min. she is diaphoretic and has a fine tremor. her eyelids are retracted, and it appears as if she is staring at you. initial laboratory evaluation reveals a decreased thyroid-stimulating hormone level and elevated antithyrotropin receptor antibodies. which of the following is the most likely etiology of her symptoms?