Seizure Activity in a 3-year-old Girl

Presentation

A 3-year-old African American girl presents to the emergency department for evaluation of seizure activity. Her seizures started 10 days ago as tonic episodes and progressed to full tonic-clonic movements, upward eye deviation, and apneic episodes with postictal states of drowsiness up to 3 times per day. She has also had more anxiety, increased clumsiness, and intermittent jerks over the past month. Her medical history is notable for speech delay (started speaking at age 2), reactive airway disease, and avoidance of all egg and dairy products due to presumed food allergies. Family history is significant for vitamin D deficiency in her maternal grandmother. Her growth parameters include a height of 95.8 cm (58th percentile), weight of 17.1 kg (92nd percentile), and BMI at the 97th percentile. Physical examination is significant for a prominent forehead, round face, mild bilateral ptosis, tetany, and positive Chvostek sign. Her musculoskeletal examination is normal. During the examination, she intermittently jerks her extremities, followed by crying; she does not follow commands.

Electrolytes are obtained and reveal low calcium at 4.7 mg/dL (reference range, 8.8–10.8 mg/dL), high phosphorus at 10.2 mg/dL (reference range, 3.2–5.8 mg/dL), and normal albumin, sodium, magnesium, and glucose levels. Parathyroid hormone (PTH) is elevated at 2,597 pg/mL (reference range, 12–88 pg/mL), alkaline phosphatase is elevated at 643 IU/L (reference range, 100–320 IU/L), 25-hydroxy vitamin D is low at 8.69 ng/mL (reference range, >30 ng/mL), and 1,25-hydroxy vitamin D is 78.5 pg/mL (reference range, 19.9–78.5 pg/mL). Blood urea nitrogen and creatinine are normal. Thyrotropin is normal at 3.439 mIU/mL (reference range, 0.5–5.0 mIU/mL) with a free thyroxine of 0.76 ng/dL (reference range, …