Review Question - QID 215110

A 45-year-old woman presents to her primary care clinic with concerns about her increased anxiety and new heart palpitations over the past 2 months. She has trouble falling asleep and constantly feels fatigued. Despite no recent dietary changes, the patient has lost 10 pounds. Her past medical history is unremarkable. She denies any drug use. Her family history is significant for a mother and aunt with rheumatoid arthritis. Her temperature is 98.4°F (36.9°C), blood pressure is 142/90 mmHg, pulse is 116/min, and respirations are 12/min. Physical exam is notable for a nontender, diffusely enlarged mass of the anterior neck and fine hand tremors. Ocular exam is significant for conjunctival hyperemia as well as superior and inferior scleral show bilaterally. Lead I of the patient’s electrocardiogram is shown in Figure A. Which of the following is the most appropriate next step in management for this patient?