Fibroblast growth factor-23 and phosphorus metabolism.

The understanding of phosphorus metabolism has expanded considerably over the last decade. Recent studies have identified a novel bone-kidney endocrine axis that maintains phosphate homeostasis. When phosphate is in excess, FGF-23 is secreted from bone and acts on the kidney to promote phosphate excretion into urine and to suppress vitamin D synthesis, thereby inducing negative phosphate balance. This review summarizes the role of the FGF-23 axis on phosphorus metabolism, and presents the clinical entities that arise from activation or inactivation of the FGF-23 axis.