RESUMO
Denosumab is a RANK-L inhibitor used off-label as a treatment for a variety of pediatric bone disorders, including aneurysmal bone cysts (ABC). Rebound hypercalcemia is a known side effect after denosumab therapy and is more commonly reported in pediatric patients. Although there are no established treatment guidelines, denosumab-induced rebound hypercalcemia is usually managed with a combination of intravenous fluids, diuretics, corticosteroids, denosumab, and/or bisphosphonates. We present the case of a 10-year-old female patient with history of a right sacral ABC treated with denosumab who presented with recurrent episodes of rebound hypercalcemia beginning 3 months after denosumab cessation. After the third hospitalization for hypercalcemia, which was treated with zoledronic acid, normocalcemia was achieved. This case demonstrates an increasingly recognized side effect of denosumab therapy that occurs mainly in skeletally immature patients and presents a possible approach to initial therapy of rebound hypercalcemia with a long-acting bisphosphonate.
RESUMO
HDR syndrome is a rare genetic disorder caused by mutations in the GATA3 gene and characterized by hypoparathyroidism, sensorineural deafness, and renal disease. Here, we report case of a 9-month-old male with history of hydronephrosis and sensorineural deafness who presented with febrile seizures. He was found to have hypocalcemia and inappropriately normal parathyroid hormone. His neurologic and infectious workup were negative. Genetic testing revealed a nonsense mutation in the GATA3 gene, consistent with HDR syndrome. Hypocalcemia was responsive to calcium carbonate and calcitriol treatment. This case highlights hypocalcemia caused by hypoparathyroidism as a potential etiology of seizures. When hypoparathyroidism is detected with either hearing loss or renal disease, HDR syndrome should be considered, and other features of the syndrome should be investigated.
