Hyperthyroidism and Graves disease — branching viva

A thirteen-year-old girl presents with palpitations, tremor, weight loss despite an increased appetite, heat intolerance, anxiety, declining school performance and prominent eyes, with a diffuse goitre and a bruit. Her thyroid function shows a suppressed TSH, a raised free T4 and a positive TSH-receptor antibody. The examiner asks: what is the diagnosis, how does the antibody produce the clinical and biochemical picture, how do you confirm it, what is the first-line management and why is propylthiouracil avoided — then branches to a two-week-old infant of a mother with a burnt-out Graves disease who is tachycardic and failing to thrive, and asks you to explain the neonatal mechanism, the natural history and the surveillance rule, before closing on a thyrotoxic adolescent who has stopped taking her tablets and presents febrile and confused.