THE CASE
A 51-year-old Japanese woman presented with fever, sore throat, and dyspnea of less than 1 day’s duration. Although she had developed general fatigue, palpitations, and tremors of the hands 2 months earlier, she had not sought medical care.
Her medical history included Graves disease, which had been diagnosed 13 years earlier. She reported that her only medication was methimazole 10 mg/d. She did not have any family history of endocrinopathies or hematologic diseases.
Physical examination revealed a body temperature of 99.7 °F; heart rate, 130 beats/min; blood pressure, 182/62 mm Hg; respiratory rate, 46 breaths/min; and oxygen saturation, 100% on room air. Pharyngeal erythema was seen. Lung sounds were clear. The patient had tremors in her hands, tenderness of the thyroid gland, and exophthalmos. No leg edema or jugular vein distension was seen.
Laboratory tests indicated hyperthyroidism, with a thyroid-stimulating hormone level < 0.01 µIU/mL (normal range, 0.5-5 µIU/mL); free T3 level, 4.87 pg/mL (normal range, 2.3-4.3 pg/mL); and free T4 level, 2.97 ng/dL (normal range, 0.9-1.7 ng/dL). The patient also had a white blood cell (WBC) count of 1020 cells/µL (normal range, 3500-9000 cells/µL) and neutrophil count of 5 cells/µL (normal range, 1500-6500 cells/µL).
Other blood cell counts were normal, and a chest x-ray did not reveal any abnormal findings. In addition, there was no evidence to suggest hematologic malignancies or congenital neutropenia.
THE DIAGNOSIS
Based on the patient’s low WBC and neutrophil counts, agranulocytosis due to antithyroid drug therapy was suspected; however, this diagnosis would be highly unusual in the context of a 13-year history of therapy. Further history taking revealed that, because of her lack of financial means, unstable living conditions, and lack of understanding of the necessity for medication adherence, the patient had not taken methimazole regularly until 2 months prior to presentation, when she started taking it because of worsening symptoms. She had hesitated to report her social and medication status due to embarrassment.
In consideration of these factors, a diagnosis of exacerbation of hyperthyroidism and agranulocytosis (due to methimazole restart and upper respiratory infection) was made.
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