title: Persistent elevation of fibroblast growth factor 23 concentrations in healthy appropriate-for-gestational-age preterm infants.
abstract: OBJECTIVE
  To explore the temporal evolution of 25-hydroxyvitamin D [25(OH)D], its epimer, parathyroid hormone (PTH), fibroblast growth factor 23 (FGF23), and minerals in healthy appropriate-for-gestational-age preterms.
  
  
  METHODS
  A prospective study was undertaken in infants born at 28-32 weeks with monitoring at 1, 3, 5 weeks and term.
  
  
  METHODS
  Morning plasma and urine calcium; phosphorus; creatinine; PTH, C-terminal and intact FGF23 (iFGF23) and liquid chromatography-tandem mass spectrometry measurements of 25(OH)D were undertaken. Analyses included regression models.
  
  
  RESULTS
  Some 11 infants (5 males) were recruited at a median gestational age of 31.2 weeks (interquartile range: 28.1-31.8). Standard chemistries were normal. No infant was vitamin D deficient; 58% achieved 50 nmol/L with a median intake of 540 IU/day. High concentrations of C-3 epimer were detected. iFGF23 and C-terminal concentrations were persistently elevated (double and ten times adult norms, respectively). Tubular resorption of phosphorus was normal (88%±8%).
  
  
  CONCLUSIONS
  Most infants achieved acceptable 25(OH)D3 concentrations. The biologic significance of the elevated FGF23 is unclear.
authors.forename: Tarah
authors.initials: T
authors.lastname: Fatani
authors.forename: Asma
authors.initials: A
authors.lastname: Binjab
authors.forename: Hope
authors.initials: H
authors.lastname: Weiler
authors.forename: Atul
authors.initials: A
authors.lastname: Sharma
authors.forename: Celia
authors.initials: C
authors.lastname: Rodd
mesh_terms: D000328:Adult; D000802:Angiotensin Amide / Q000097:blood*; D015415:Biomarkers / Q000097:blood*; D016022:Case-Control Studies; D002853:Chromatography, Liquid; D016640:Diabetes, Gestational / Q000097:blood / Q000503:physiopathology*; D005260:Female; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000097:blood*; D005500:Follow-Up Studies; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature / Q000097:blood*; D008297:Male; D011225:Pre-Eclampsia / Q000097:blood / Q000503:physiopathology*; D011247:Pregnancy; D011379:Prognosis; D011446:Prospective Studies; D053719:Tandem Mass Spectrometry; D047929:Term Birth
chemical_list: D015415:Biomarkers; C000717427:FGF23 protein, human; D000802:Angiotensin Amide; D005346:Fibroblast Growth Factors; D000089703:Fibroblast Growth Factor-23