A 13-year-old girl presents to the pediatric clinic with complaints of malaise, progressive nausea, emesis, and poor oral intake since removal of her wisdom teeth 1 month earlier. In that month she completed a course of clindamycin to treat a suspected postoperative oral infection. Review of systems revealed a 10-lb unintentional weight loss, intermittent joint pain, and decreased urine output. She denies any fevers.
Vital signs are normal other than blood pressure of 130/72 mm Hg and pulse of 121 beats/min. Physical examination shows a tired-appearing but polite young lady with a slightly enlarged, asymmetrical thyroid and otherwise normal examination findings.
A complete blood cell count shows a hemoglobin level of 11.6 g/dL (116 g/L), a platelet count of 0.153 × 103/mcL (0.153 × 109/L), and a white blood cell count of 5.3/µL (0.01 × 109/L) with a normal differential cell count. Thyrotropin and...