Regulation of phosphate homeostasis in infants, children, and adolescents, and the role of phosphatonins in this process.
OBJECTIVE
Unlike calcium metabolism, the control of phosphate homeostasis has long been poorly understood. The identification of 'phosphatonins' in the serum of hypophosphatemic patients, the unveiling of the genetic causes of hypo and hyperphosphatemic diseases in patients, and the creation of finely adapted animal models have revolutionized our understanding of phosphate homeostasis.


RESULTS
Original reports published in 2006/2007 bring valuable pieces of information that enable better understanding of the physiological regulation of phosphate homeostasis by more precisely defining the interplay between PHEX, vitamin D, and phosphatonins; identification of new genes causing hypophosphatemic rickets, aside from PHEX and fgf23, namely the genes encoding for a renal sodium-phosphate cotransporter, NaPiIIc, and for a bone matrix protein, DmpI; and improved diagnosis of tumor-induced osteomalacia with more precise imaging techniques for tumor localization and more precise fibroblast growth factor 23 assays.


CONCLUSIONS
From a clinical point of view, these findings offer new tools for the diagnosis of hypophosphatemic rickets (biologic, genetic, imaging techniques) and open the way to new treatment strategies.
Garabedian
Michele
M
Inserm U561, St Vincent de Paul Hospital, Paris, France. cnrs.svp@wanadoo.fr
D000293:Adolescent; D002648:Child; D053098:Familial Hypophosphatemic Rickets / Q000235:genetics; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000097:blood; D006706:Homeostasis; D006801:Humans; D017674:Hypophosphatemia / Q000175:diagnosis / Q000209:etiology / Q000235:genetics / Q000503:physiopathology*; D007223:Infant; D010018:Osteomalacia / Q000209:etiology; D053402:PHEX Phosphate Regulating Neutral Endopeptidase / Q000502:physiology; D010710:Phosphates / Q000502:physiology*
C000717427:FGF23 protein, human; D010710:Phosphates; D005346:Fibroblast Growth Factors; D000089703:Fibroblast Growth Factor-23; D053402:PHEX Phosphate Regulating Neutral Endopeptidase; C506231:PHEX protein, human