Thyrotoxicosis factitia complicating Graves' disease

A patient with Graves' disease remained clinically and biochemically hyperthyroid after intravenous therapeutic(131)I, although thyroidal uptake fell to normal. Previously she had taken antithyroid drugs irregularly and vomited twice after oral(131)I. She was treated with carbimazole and thyroxine 0.2 mg daily because of severe exophthalmos. However, she maintained her hypermetabolic state by surreptitiously taking thyroxine in excess of the prescribed dose. When drug treatment was stopped under supervision she rapidly became euthyroid. By tracing prescriptions supplied to the patient it was shown that she had obtained amounts of thyroxine grossly in excess of her requirements.