title: Effects of acute kidney injury and chronic hypoxemia on fibroblast growth factor 23 levels in pediatric cardiac surgery patients.
abstract: BACKGROUND
  Fibroblast growth factor-23 (FGF23) levels are elevated in cardiopulmonary bypass (CPB)-associated acute kidney injury (AKI); however, it is unknown how much of the circulating FGF23 is intact and bioactive. Hypoxia may induce FGF23 production, yet its impact in humans is unknown. Pediatric cardiac surgery patients have both a high incidence of CPB-associated AKI and a high prevalence of chronic hypoxemia.
  
  
  METHODS
  We assessed the effects of hypoxemia and CPB-associated AKI on C-terminal FGF23 (cFGF23) and intact FGF23 (iFGF23) levels in 32 pediatric cardiac surgery patients with normal estimated glomerular filtration rate (eGFR). Plasma cFGF23 and iFGF23 were measured preoperatively and serially postoperatively.
  
  
  RESULTS
  Despite normal renal and ventricular function, preoperative cFGF23 levels were high and elevated out of proportion to iFGF23 levels. Preoperative oxygen saturation measurements correlated inversely with FGF23 levels. Preoperative cFGF23 and oxygen saturation both predicted postoperative AKI. Postoperatively, cFGF23 and iFGF23 increased by 2 h postreperfusion; iFGF23 then returned to baseline, but cFGF23 remained elevated through 24 h postreperfusion. Group status (AKI vs. non-AKI) modified the effect of time on changes in iFGF23 levels but not cFGF23 levels.
  
  
  CONCLUSIONS
  Preoperative cFGF23 may predict CPB-associated kidney dysfunction. Changes over time in cFGF23 and iFGF23 levels post-CPB differ. Chronic hypoxemia may affect FGF23 production in humans.
authors.affiliation: Departments of Pediatrics, David Geffen School of Medicine at UCLA, 10833 Le Conte Avenue, MDCC A2-383, Los Angeles, CA, 90095-1752, USA. mhanudel@mednet.ucla.edu.
authors.forename: Mark R
authors.initials: MR
authors.lastname: Hanudel
authors.affiliation: Departments of Pediatrics, David Geffen School of Medicine at UCLA, 10833 Le Conte Avenue, MDCC A2-383, Los Angeles, CA, 90095-1752, USA.
authors.forename: Katherine
authors.initials: K
authors.lastname: Wesseling-Perry
authors.affiliation: Departments of Pediatrics, David Geffen School of Medicine at UCLA, 10833 Le Conte Avenue, MDCC A2-383, Los Angeles, CA, 90095-1752, USA.
authors.forename: Barbara
authors.initials: B
authors.lastname: Gales
authors.affiliation: Departments of Pediatrics, David Geffen School of Medicine at UCLA, 10833 Le Conte Avenue, MDCC A2-383, Los Angeles, CA, 90095-1752, USA.
authors.forename: Georgina
authors.initials: G
authors.lastname: Ramos
authors.affiliation: Departments of Pediatrics, David Geffen School of Medicine at UCLA, 10833 Le Conte Avenue, MDCC A2-383, Los Angeles, CA, 90095-1752, USA.
authors.forename: Vicky
authors.initials: V
authors.lastname: Campbell
authors.affiliation: Departments of Pediatrics, David Geffen School of Medicine at UCLA, 10833 Le Conte Avenue, MDCC A2-383, Los Angeles, CA, 90095-1752, USA.
authors.forename: Kristen
authors.initials: K
authors.lastname: Ethridge
authors.affiliation: Departments of Pediatrics, David Geffen School of Medicine at UCLA, 10833 Le Conte Avenue, MDCC A2-383, Los Angeles, CA, 90095-1752, USA.
authors.forename: Mary
authors.initials: M
authors.lastname: Scotti
authors.affiliation: Departments of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
authors.forename: David A
authors.initials: DA
authors.lastname: Elashoff
authors.affiliation: Departments of Pediatrics, David Geffen School of Medicine at UCLA, 10833 Le Conte Avenue, MDCC A2-383, Los Angeles, CA, 90095-1752, USA.
authors.forename: Juan
authors.initials: J
authors.lastname: Alejos
authors.affiliation: Departments of Pediatrics Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
authors.forename: Brian
authors.initials: B
authors.lastname: Reemtsen
authors.affiliation: Departments of Pediatrics, David Geffen School of Medicine at UCLA, 10833 Le Conte Avenue, MDCC A2-383, Los Angeles, CA, 90095-1752, USA.
authors.forename: Isidro B
authors.initials: IB
authors.lastname: Salusky
mesh_terms: D058186:Acute Kidney Injury / Q000097:blood* / Q000175:diagnosis / Q000209:etiology; D015415:Biomarkers / Q000097:blood; D006348:Cardiac Surgical Procedures / Q000009:adverse effects*; D002315:Cardiopulmonary Bypass / Q000009:adverse effects*; D002648:Child; D002675:Child, Preschool; D002908:Chronic Disease; D005260:Female; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000097:blood*; D006801:Humans; D000860:Hypoxia / Q000097:blood* / Q000175:diagnosis / Q000209:etiology; D007223:Infant; D008297:Male; D010446:Peptide Fragments / Q000097:blood*; D011237:Predictive Value of Tests; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D015415:Biomarkers; C000717427:FGF23 protein, human; D010446:Peptide Fragments; D005346:Fibroblast Growth Factors; D000089703:Fibroblast Growth Factor-23
keywords: Acute kidney injury; Cardiac surgery; Chronic hypoxemia; Fibroblast growth factor 23; Pediatrics