title: Iron Supplementation Associated With Loss of Phenotype in Autosomal Dominant Hypophosphatemic Rickets.
abstract: BACKGROUND
  Autosomal dominant hypophosphatemic rickets (ADHR) is the only hereditary disorder of renal phosphate wasting in which patients may regain the ability to conserve phosphate. Low iron status plays a role in the pathophysiology of ADHR.
  
  
  OBJECTIVE
  This study reports of a girl with ADHR, iron deficiency, and a paternal history of hypophosphatemic rickets that resolved without treatment. The girl's biochemical phenotype resolved with iron supplementation.
  
  
  METHODS
  A 26-month-old girl presented with typical features of hypophosphatemic rickets, short stature (79 cm; -2.82 SDS), and iron deficiency. Treatment with elemental phosphorus and calcitriol improved her biochemical profile and resolved the rickets. The girl's father had presented with rickets at age 11 months but never received medication. His final height was reduced (154.3 cm; -3.51 SDS), he had undergone corrective leg surgery and had an adult normal phosphate, fibroblast growth factor 23, and iron status. Father and daughter were found to have a heterozygous mutation in exon 3 of the FGF23 gene (c.536G>A, p.Arg179Gln), confirming ADHR.
  
  
  METHODS
  Withdrawal of rickets medication was attempted off and on iron supplementation.
  
  
  RESULTS
  Withdrawal of rickets medication in the girl was unsuccessful in the presence of low-normal serum iron levels at age 5.6 years but was later successful in the presence of high-normal serum iron levels following high-dose iron supplementation.
  
  
  CONCLUSIONS
  We report an association between iron supplementation and a complete loss of biochemical ADHR phenotype, allowing withdrawal of rickets medication. Experience from this case suggests that reduction and withdrawal of rickets medication should be attempted only after iron status has been optimized.
authors.affiliation: Department of Pediatrics (K.K., J.K.), Medical University of Innsbruck, 6020 Innsbruck, Austria; Department of Pediatrics (J.K.), Technische Universität München, 80333 München, Germany; Division of Human Genetics, Department for Medical Genetics, Molecular and Clinical Pharmacology (D.K.), Medical University of Innsbruck, 6020 Innsbruck, Austria; and Department of Endocrinology and Diabetes (W.H.), Birmingham Children's Hospital, Birmingham B4 6NH, United Kingdom.
authors.forename: Klaus
authors.initials: K
authors.lastname: Kapelari
authors.affiliation: Department of Pediatrics (K.K., J.K.), Medical University of Innsbruck, 6020 Innsbruck, Austria; Department of Pediatrics (J.K.), Technische Universität München, 80333 München, Germany; Division of Human Genetics, Department for Medical Genetics, Molecular and Clinical Pharmacology (D.K.), Medical University of Innsbruck, 6020 Innsbruck, Austria; and Department of Endocrinology and Diabetes (W.H.), Birmingham Children's Hospital, Birmingham B4 6NH, United Kingdom.
authors.forename: Julia
authors.initials: J
authors.lastname: Köhle
authors.affiliation: Department of Pediatrics (K.K., J.K.), Medical University of Innsbruck, 6020 Innsbruck, Austria; Department of Pediatrics (J.K.), Technische Universität München, 80333 München, Germany; Division of Human Genetics, Department for Medical Genetics, Molecular and Clinical Pharmacology (D.K.), Medical University of Innsbruck, 6020 Innsbruck, Austria; and Department of Endocrinology and Diabetes (W.H.), Birmingham Children's Hospital, Birmingham B4 6NH, United Kingdom.
authors.forename: Dieter
authors.initials: D
authors.lastname: Kotzot
authors.affiliation: Department of Pediatrics (K.K., J.K.), Medical University of Innsbruck, 6020 Innsbruck, Austria; Department of Pediatrics (J.K.), Technische Universität München, 80333 München, Germany; Division of Human Genetics, Department for Medical Genetics, Molecular and Clinical Pharmacology (D.K.), Medical University of Innsbruck, 6020 Innsbruck, Austria; and Department of Endocrinology and Diabetes (W.H.), Birmingham Children's Hospital, Birmingham B4 6NH, United Kingdom.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Högler
mesh_terms: D002117:Calcitriol / Q000627:therapeutic use*; D002675:Child, Preschool; D019587:Dietary Supplements; D053098:Familial Hypophosphatemic Rickets / Q000188:drug therapy*; D005260:Female; D000089703:Fibroblast Growth Factor-23; D006801:Humans; D007501:Iron / Q000627:therapeutic use*; D000090463:Iron Deficiencies; D012279:Rickets / Q000188:drug therapy*; D016896:Treatment Outcome
chemical_list: C000717427:FGF23 protein, human; D000089703:Fibroblast Growth Factor-23; D007501:Iron; D002117:Calcitriol