RESUMEN
Two pediatric patients with different causes of hyperparathyroidism are reported. First patient is a 13-year-old male with severe hypercalcemia due to left upper parathyroid gland adenoma. After successful surgery, calcium and phosphate levels normalized, but parathormone levels remained elevated. Further studies revealed a second adenoma in the right gland. The second patient is a 13-year-old female with uncommon hypercalcemia symptoms. Presence of pathogenic calcium-sensing receptor gene (CASR) mutation was found, resulting in diagnosis of symptomatic familial hypocalciuric hypercalcemia. Cinacalcet, a calcium-sensing agent that increases the sensitivity of the CASR, was used in both patients with successful results. LEARNING POINTS: Hyperparathyroidism is a rare condition in pediatric patients. If not treated, it can cause serious morbidity.Genetic tests searching for CASR or MEN1 gene mutations in pediatric patients with primary hyperparathyroidism should be performed.Cinacalcet has been effective for treating different causes of hyperparathyroidism in our two pediatric patients.Treatment has been well tolerated and no side effects have been detected.