title: Association of serum levels of FGF23 and α-Klotho with glomerular filtration rate and proteinuria among cardiac patients.
abstract: BACKGROUND
  Expression and/or excretion of fibroblast growth factor-23 (FGF23) and its co-receptor Klotho are altered in patients with end-stage renal disease. The possibility that the FGF23/α-Klotho system mediates the aggravated cardiovascular outcome among patients with chronic kidney disease (CKD) has been suggested. We determined whether FGF23 and α-Klotho concentrations are altered among patients with reduced renal function and proteinuria.
  
  
  METHODS
  Serum FGF23 and α-Klotho were measured in cardiology patients who were not undergoing chronic hemodialysis. Estimated glomerular filtration rate (eGFR) was correlated negatively with FGF23 and positively with α-Klotho.
  
  
  RESULTS
  The correlation between FGF23 and the renal tubular maximum reabsorption rate of phosphate to the GFR (TmP/GFR) was not significant, but that between FGF23 and serum calcium or inorganic phosphate was significant among patients with an estimated GFR of less than 60 mL/min/m(2). By stepwise multivariate regression analysis, eGFR was selected as significant predictor for FGF23 or α-Klotho among patients with an estimated GFR of less than 60 mL/min/m(2); however, urine albumin/creatinine ratio was not selected as a predictor for FGF23 or α-Klotho irrespective of the eGFR levels. In patients with eGFR of <60 mL/min/1.73 m(2), UACR was significantly associated with log(FGF23); but, this association did not remain statistically significant in a multivariate model.
  
  
  CONCLUSIONS
  Among cardiology patients with various stages of CKD, serum concentrations of FGF23 and α-Klotho were associated with renal function, but not with the extent of proteinuria.
authors.forename: Michishige
authors.initials: M
authors.lastname: Ozeki
authors.forename: Shu-ichi
authors.initials: S
authors.lastname: Fujita
authors.forename: Shun
authors.initials: S
authors.lastname: Kizawa
authors.forename: Hideaki
authors.initials: H
authors.lastname: Morita
authors.forename: Koichi
authors.initials: K
authors.lastname: Sohmiya
authors.forename: Masaaki
authors.initials: M
authors.lastname: Hoshiga
authors.affiliation: Department of Cardiology, Osaka Medical College, Takatsuki-shi Daigaku-machi 2-7, Osaka 569-8686, Japan. ishizaka@poh.osaka-med.ac.jp.
authors.forename: Nobukazu
authors.initials: N
authors.lastname: Ishizaka
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood; D002318:Cardiovascular Diseases / Q000097:blood* / Q000175:diagnosis / Q000453:epidemiology; D005260:Female; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000097:blood*; D005919:Glomerular Filtration Rate / Q000502:physiology*; D005966:Glucuronidase / Q000097:blood*; D006801:Humans; D000090265:Klotho Proteins; D008297:Male; D008875:Middle Aged; D011507:Proteinuria / Q000097:blood* / Q000175:diagnosis / Q000453:epidemiology; D012189:Retrospective Studies
chemical_list: D015415:Biomarkers; C000717427:FGF23 protein, human; D005346:Fibroblast Growth Factors; D000089703:Fibroblast Growth Factor-23; D005966:Glucuronidase; D000090265:Klotho Proteins