Pediatric Nephrology

, Volume 25, Issue 4, pp 591-601

First online:

Regulation of phosphate transport by fibroblast growth factor 23 (FGF23): implications for disorders of phosphate metabolism

  • Jyothsna GattineniAffiliated withDepartment of Pediatrics, University of Texas Southwestern Medical Center at Dallas
  • , Michel BaumAffiliated withDepartment of Pediatrics, University of Texas Southwestern Medical Center at DallasDepartment of Internal Medicine, University of Texas Southwestern Medical Center at Dallas Email author 

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There are a number of hypophosphatemic disorders due to renal phosphate wasting that cannot be explained by elevated levels of parathyroid hormone. The circulating factors responsible for the phosphaturia have been designated as phosphatonins. Studies of patients with tumor-induced osteomalacia and other genetic diseases of phosphate metabolism have resulted in the identification of a number of hormones that regulate phosphate homeostasis, including matrix extracellular phosphoglycoprotein (MEPE), secreted frizzled-related protein 4 (sFRP-4), dentin matrix protein 1 (DMP1), fibroblast growth factor 7 (FGF7), fibroblast growth factor 23 (FGF23), and Klotho. Our understanding of the actions of these hypophosphatemic peptides has been enhanced by studies in mice either overexpressing or not expressing these hormones. This review focuses on FGF23 since its regulation is disordered in diseases that affect children, such as X-linked hypophosphatemia, autosomal dominant and recessive hypophosphatemic rickets as well as chronic kidney disease. Recent studies have shown that FGF23 is unique among the FGFs in its requirement for Klotho for receptor activation. Here, we also discuss new potentially clinically important data pointing to the receptor(s) that mediate the binding and action of FGF23 and Klotho.


Hypophosphatemia Klotho Proximal tubule Sodium phosphate cotransporter