Adequate 25-OH-Vitamin D Level and Calcium Intake Enhance the Efficacy of Teriparatide in Gain-of-Function Mutation in Calcium-Sensing Receptor Defect, A Case Report

Gain-of-function mutations in the calcium-sensing receptor (CaSR) result in congenital hypoparathyroidism, characterized by suppressed parathyroid hormone (PTH) secretion, hypocalcemia, hyperphosphatemia and hypercalciuria. Managing hypocalcemia in these patients is challenging, as conventional therapy with calcium and active vitamin D analog supplementation often exacerbates renal complications. Teriparatide, a recombinant PTH (1-34) analog, has been approved as an alternative treatment in adult patient. However, data on its prolonged use in pediatric patients remain limited. We present a pediatric case of teriparatide therapy for hypoparathyroidism due to a de novo CaSR mutation, spanning more than 10 years from infancy into late childhood. In this case, the importance of adequate supplementation of native vitamin D and calcium was illustrated by the drastic reduction in teriparatide dosage requirement. In this case, satisfactory growth without major side effects and static nephrocalcinosis were demonstrated during long-term teriparatide therapy. Further studies are required to define optimal PTH analog dosage in pediatric patient, to evaluate extended therapeutic outcomes, and explore real-time calcium monitoring strategies to refine management in congenital hypoparathyroidism.