Evaluation and Treatment of Disorders of Phosphate Balance

Abstract

The purpose of this article is to review (1) the molecular mechanisms and hormonal factors involved in phosphate handling and regulation, (2) how to appropriately interpret serum and urine phosphate measurements in pediatric patients, (3) the pathophysiology of hypophosphatemic and hyperphosphatemic conditions, and (4) current strategies for treatment of hypophosphatemia and hyperphosphatemia in pediatric patients. For decades, treatment of some hypophosphatemic conditions like X-linked hypophosphatemic rickets (XLH), characterized by a primary increase in fibroblast growth factor 23 (FGF23) activity, consisted of non-specific therapy with phosphate supplementation and calcitriol administration. However, in the past few years, burosumab, a targeted anti-FGF23 antibody, has been developed, representing a promising new medication for the treatment of pediatric XLH patients. The treatment of hyperphosphatemic conditions like chronic kidney disease (CKD) consists of dietary phosphate restriction and enteral phosphate binders; however, the development of new binders and inhibitors of cellular phosphate transporters may offer additional treatment options in the future. The evaluation and treatment of disorders of phosphate balance in children is complex, as numerous interrelated mechanisms and hormones are involved in phosphate handling and regulation. Knowledge of the pathophysiology of hypophosphatemic and hyperphosphatemic conditions informs optimal diagnostic and treatment strategies.