Childhood Diseases of the Thyroid and Parathyroid Glands

A 15-year-old girl is brought to the pediatrician by her mother due to concerns about unexplained weight loss and irritability over the past 3 months. Her mother notes she has been eating more than usual but has lost 4 kg. The patient reports feeling "jittery" all the time, having difficulty sleeping, and experiencing occasional palpitations. On physical exam, she is afebrile with a heart rate of 112 bpm and a blood pressure of 136/82 mmHg. She has a fine tremor in her outstretched hands. Examination of her neck reveals a diffusely enlarged, non-tender thyroid gland without distinct nodules. You note a slight lid lag and mild exophthalmos.