MSRA-0452

A 42-year-old woman visits her GP with concerns of feeling constantly overheated and experiencing early menopause. Her husband has also noticed a swelling in her neck over the past few weeks. During the examination, her pulse is recorded at 90/minute, and a small, painless goitre is observed. The doctor orders blood tests, which reveal the following results: TSH < 0.05 mu/l, Free T4 24 pmol/l, Anti-thyroid peroxidase antibodies 102 IU/mL (< 35 IU/mL), and ESR 23 mm/hr. What is the most probable diagnosis?