Hyperthyroidism/ Graves disease

Answer questions to the provided case study uses the sources attached.
A 27-year-old woman presents to your office complaining of progressing nervousness, fatigue, palpitations, and the recent development of a resting hand
tremor. She also states that she is having difficulty concentrating at work and has been more irritable with her coworkers. The patient also notes that she has
developed a persistent rash over her shins that has not improved with the use of topical steroid creams. All of her symptoms have come on gradually over
the past few months and continue to get worse. Review of systems also reveals an unintentional weight loss of about 10 lb, insomnia, and amenorrhea for
the past 2 months (the patient’s menstrual cycles are usually quite regular). The patient’s past medical history is unremarkable and she takes no oral
medications. She is currently not sexually active and does not drink alcohol, smoke, or use any illicit drugs. On examination, she is afebrile. Her pulse varies
from 70 to 110 beats/min. She appears restless and anxious. Her skin is warm and moist. Her eyes show evidence of exophthalmos and lid retraction
bilaterally, although funduscopic examination is normal. Neck examination reveals symmetric thyroid enlargement, without any discrete palpable masses.
Cardiac examination reveals an irregular rhythm. Her lungs are clear to auscultation. Extremity examination reveals an erythematous, thickened rash on both
shins. Neurologic examination is normal except for a fine resting tremor in her hands when she attempts to hold out her outstretched arms. Initial laboratory
tests include a negative pregnancy test and an undetectable level of thyroid-stimulating hormone (TSH).
1) What is the most likely diagnosis? Provide your rationales
2) What imaging study is most appropriate at this time?
3) What is the definitive nonsurgical treatment of this condition?