AKT-4650

A 35-year-old woman presents with excessive sweating and weight loss. Her partner reports that she is constantly on edge and you notice a fine tremor during the consultation. A large, non-tender goitre is also noted. However, examination of her eyes reveals no exophthalmos.

Free T4 levels are at 26 pmol/l, while Free T3 levels are at 12.2 pmol/l (3.0-7.5). Her TSH levels are less than 0.05 mu/l. What is the most probable diagnosis?