[FGF23 and skeletal metabolism].

FGF23 is an endocrine FGF produced by osteocytes, which increases excretion of phosphate and suppresses the production of 1,25 (OH) 2D. Excessive action of FGF23 causes various forms of hypophosphatemic rickets/osteomalacia, while the loss of function of FGF23 results in the condition called familial hyperphosphatemic tumoral calcinosis. 1,25 (OH) 2D stimulates the production of FGF23, and the interaction between FGF23 and 1,25 (OH) 2D plays a central role in mineral homeostasis. In addition to the its roles in mineral homeostasis, recent studies have suggested the direct action of FGF23 on osteoblasts and chondrocytes.