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JAMA Clinical Challenge
June 2, 2015

Enlarged Thymus in a Patient With Dyspnea and Weight Loss

Author Affiliations
  • 1Division of Endocrinology, Metabolism and Molecular Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois
JAMA. 2015;313(21):2174-2175. doi:10.1001/jama.2015.2713

A 36-year-old woman reported experiencing shortness of breath for 1 month. She reported a 6.3-kg weight loss, tremor, diaphoresis, and palpitations over the course of 2 months. She denied eye symptoms or muscle weakness. Physical examination revealed tachycardia, tongue and hand tremors, no exophthalmos, a 2-fold diffusely enlarged thyroid gland, and brisk reflexes.

Laboratory results showed a thyroid-stimulating hormone (TSH) level of 0.005 mIU/L (normal, 0.45-4.50 mIU/L), free thyroxine level greater than 7.77 ng/dL (100.01 pmol/L) (normal, 0.82-1.77 ng/dL [10.55-22.78 pmol/L]), free triiodothyronine level of 30.6 pg/mL (47.1 pmol/L) (normal, 2.0-3.9 pg/mL [3.08-6.01 pmol/L]), and thyroid-stimulating immunoglobulin index of 5.5 (normal, <1.3). The patient began treatment with methimazole, 20 mg twice daily.