title: Serum fibroblast growth factor 23 is a useful marker to distinguish vitamin D-deficient rickets from hypophosphatemic rickets.
abstract: OBJECTIVE
  Vitamin D-deficient rickets (DR) has recently re-emerged among developed countries. Vitamin D deficiency can influence biochemical results of patients with fibroblast growth factor 23 (FGF23)-related hereditary hypophosphatemic rickets (HR), making differential diagnosis difficult. In the present study we evaluated the utility of serum FGF23 levels in the diagnosis of DR and during its treatment.
  
  
  METHODS
  The study group comprised 24 children with DR and 8 children with HR. Serum FGF23 levels and bone metabolism-related measurements were assessed.
  
  
  RESULTS
  Serum FGF23 levels in patients with DR were less than 19 pg/ml, while those in patients with HR were more than 57 pg/ml. There were significant differences in serum levels of calcium, phosphate, parathyroid hormone, and 1,25-dihydroxyvitamin D, as well as tubular maximum phosphate reabsorption per glomerular filtration rate between patients with DR and HR, but these values were not fully mutually exclusive. In addition, serum FGF23 and phosphate levels were increased following treatment.
  
  
  CONCLUSIONS
  Serum FGF23 level is the most critical biochemical marker for distinguishing DR from HR and might be a good indicator of biochemical response to the intervention. Serum FGF23 levels show utility for the diagnosis of DR and in the assessment of its response to treatment.
authors.affiliation: Department of Pediatrics, Graduate School of Medicine, Osaka, Japan.
authors.forename: Takuo
authors.initials: T
authors.lastname: Kubota
authors.forename: Taichi
authors.initials: T
authors.lastname: Kitaoka
authors.forename: Kohji
authors.initials: K
authors.lastname: Miura
authors.forename: Makoto
authors.initials: M
authors.lastname: Fujiwara
authors.forename: Yasuhisa
authors.initials: Y
authors.lastname: Ohata
authors.forename: Yoko
authors.initials: Y
authors.lastname: Miyoshi
authors.forename: Keiko
authors.initials: K
authors.lastname: Yamamoto
authors.forename: Shinji
authors.initials: S
authors.lastname: Takeyari
authors.forename: Takehisa
authors.initials: T
authors.lastname: Yamamoto
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Namba
authors.forename: Keiichi
authors.initials: K
authors.lastname: Ozono
mesh_terms: D002675:Child, Preschool; D003937:Diagnosis, Differential; D005260:Female; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000097:blood*; D006801:Humans; D007223:Infant; D008297:Male; D012279:Rickets / Q000097:blood / Q000175:diagnosis* / Q000209:etiology; D063730:Rickets, Hypophosphatemic / Q000097:blood / Q000175:diagnosis*; D014808:Vitamin D Deficiency / Q000097:blood / Q000150:complications*
chemical_list: C000717427:FGF23 protein, human; D005346:Fibroblast Growth Factors; D000089703:Fibroblast Growth Factor-23