GRAVES' HYPERTHYROIDISM

A 42-year-old woman presented with palpitations, anxiety, tremor, and weight loss. She had received a diagnosis of Graves' disease 15 years previously but had discontinued therapy more than 5 years previously. Over the ensuing years she noticed a slowly enlarging anterior neck mass, and in the months before presentation, dyspnea and dysphagia developed. There was no hoarseness, stridor, menstrual irregularity, heart failure, or psychosis, but a widened pulse pressure, pretibial myxedema, and proximal muscle weakness were noted. She had a large, nodular, and firm goiter (Panel A), which was also visible on computed tomography of the neck (Panel B). There was evidence of eyelid retraction, diaphoresis, and jugular venous distention (Panel A and Video 1), which worsened with Pemberton's maneuver. The thyrotropin level was less than 0.004 µU per milliliter (normal range, 0.40 to 4), the triiodothyronine level was more than 600 ng per deciliter (9.2 nmol per liter) (normal range, 70 to 204 [1.1 to 3.1]), the free thyroxine level was more than 6 ng per deciliter (77.2 pmol per liter) (normal range, 0.8 to 1.9 [10.3 to 24.5]), the thyroid peroxidase antibody level was more than 1000 IU per milliliter (normal range, <35),>