Nephrological evolution of pediatric patients with x-linked hypophosphatemic rickets. case series

X-linked hypophosphatemic rickets (XLR) is a rare inherited disease characterized by abnormalities in phosphorus metabolism caused by a mutation in the PHEX gene. Biochemically, it is characterized by hypophosphatemia secondary to hyperphosphaturia and vitamin D deficiency, and clinically by bone deformities in the lower extremities and growth retardation. Conventional treatment with phosphate salts and active vitamin D has been used for over 45 years; however, it has been associated with nephrocalcinosis. Currently, a new medication for the treatment of XLR, a monoclonal antibody called Burosumab, is available and was approved for use in 2018. Method: A search was conducted of the medical records of pediatric patients diagnosed with X-linked hypophosphatemic rickets treated with burosumab, and biochemical parameters were analyzed throughout their clinical course. Results: Before burosumab administration, the patients presented with hypophosphatemia, decreased tubular reabsorption of phosphorus, insufficient vitamin D, and hypercalciuria in one patient. After 12 months of burosumab treatment, these parameters improved. Conclusion: This study provides evidence of the initial response to Burosumab treatment in pediatric patients, where biochemical improvement was observed with the introduction of Burosumab into the treatment regimen for patients with XLR, thus reducing the risk of nephrocalcinosis.