Thyrotoxicosis with a sore neck

36-year-old woman with 3 weeks of palpitations, weight loss and a painful, tender neck radiating to the jaw, which began after a sore throat. Free T4 41 pmol/L, TSH below 0.01 mU/L, ESR 78 mm/h. No eye signs, not pregnant or breastfeeding, no amiodarone and no iodinated contrast in the last 3 months. Request from the GP: 'Graves' disease? For radioiodine.'