title: Fibroblast growth factor 23 in patients undergoing peritoneal dialysis.
abstract: OBJECTIVE
  Fibroblast growth factor 23 (FGF23) is an independent risk factor for mortality in patients with ESRD. Before FGF23 testing can be integrated into clinical practice of ESRD, further understanding of its determinants is needed.
  
  
  METHODS
  In a study of 67 adults undergoing peritoneal dialysis, we tested the hypothesis that longer dialysis vintage and lower residual renal function and renal phosphate clearance are associated with higher FGF23. We also compared the monthly variability of FGF23 versus parathyroid hormone (PTH) and serum phosphate.
  
  
  RESULTS
  In unadjusted analyses, FGF23 correlated with serum phosphate (r = 0.66, P < 0.001), residual renal function (r = -0.37, P = 0.002), dialysis vintage (r = 0.31, P = 0.01), and renal phosphate clearance (r = -0.38, P = 0.008). In adjusted analyses, absence of residual renal function and greater dialysis vintage associated with higher FGF23, independent of demographics, laboratory values, peritoneal dialysis modality and adequacy, and treatment with vitamin D analogs and phosphate binders. Urinary and dialysate FGF23 clearances were minimal. In three serial monthly measurements, within-subject variability accounted for only 10% of total FGF23 variability compared with 50% for PTH and 60% for serum phosphate.
  
  
  CONCLUSIONS
  Increased serum phosphate, loss of residual renal function, longer dialysis vintage, and lower renal phosphate clearance are associated with elevated FGF23 levels in ESRD patients undergoing peritoneal dialysis. FGF23 may be a more stable marker of phosphate metabolism in ESRD than PTH or serum phosphate.
authors: Division of Nephrology and Hypertension, University of Miami Miller School of Medicine, Miami, FL 33136, USA.
authors: Tamara
authors: T
authors: Isakova
authors: Huiliang
authors: H
authors: Xie
authors: Allison
authors: A
authors: Barchi-Chung
authors: Gabriela
authors: G
authors: Vargas
authors: Nicole
authors: N
authors: Sowden
authors: Jessica
authors: J
authors: Houston
authors: Patricia
authors: P
authors: Wahl
authors: Andrew
authors: A
authors: Lundquist
authors: Michael
authors: M
authors: Epstein
authors: Kelsey
authors: K
authors: Smith
authors: Gabriel
authors: G
authors: Contreras
authors: Luis
authors: L
authors: Ortega
authors: Oliver
authors: O
authors: Lenz
authors: Patricia
authors: P
authors: Briones
authors: Phyllis
authors: P
authors: Egbert
authors: T Alp
authors: TA
authors: Ikizler
authors: Harald
authors: H
authors: Jueppner
authors: Myles
authors: M
authors: Wolf
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood / Q000652:urine; D005260:Female; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000097:blood* / Q000652:urine*; D006801:Humans; D007668:Kidney / Q000378:metabolism / Q000503:physiopathology; D007676:Kidney Failure, Chronic / Q000097:blood / Q000503:physiopathology / Q000628:therapy* / Q000652:urine; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood; D010530:Peritoneal Dialysis; D010710:Phosphates / Q000097:blood; D011237:Predictive Value of Tests; D013997:Time Factors; D016896:Treatment Outcome; D014481:United States; D015854:Up-Regulation
chemical_list: D015415:Biomarkers; C000717427:FGF23 protein, human; C470125:PTH protein, human; D010281:Parathyroid Hormone; D010710:Phosphates; D005346:Fibroblast Growth Factors; D000089703:Fibroblast Growth Factor-23