Abstract
Seizures are the most common neurological disorder in pediatrics, and their initial approach aims at clinical stabilization. A thorough patient evaluation may provide important clues for the etiological diagnosis. A 12-month-old female child was observed in the emergency department after experiencing her first apyretic seizure. She had a history of congenital alopecia and, on physical examination, presented subtotal alopecia and milia. Initial investigation revealed hypocalcemia; therefore, intravenous calcium correction was started with a partial response. The analytical study was extended, revealing hypophosphatemia, elevated parathormone, and 1,25(OH)(2) vitamin D with normal 25(OH) vitamin D. The genetic analysis confirmed hereditary vitamin D-resistant rickets (HVDRR). The integration of the findings was crucial to diagnostic reasoning and to guide further investigation. HVDRR is a rare disorder, with more severe clinical presentations associated with alopecia. Early diagnosis and treatment are fundamental to minimize the impact on growth and the development of other comorbidities.