title: Association of circulating fibroblast growth factor-23 with renal phosphate excretion among hemodialysis patients with residual renal function.
abstract: OBJECTIVE
  High serum levels of fibroblast growth factor-23 (FGF-23) are associated with mortality in patients with ESRD, but whether it still acts as a phosphaturic factor is unknown. This study aimed to explore the role of circulating FGF-23 on urinary phosphate excretion and phosphate balance in maintenance hemodialysis (MHD) patients with residual renal function (RRF).
  
  
  METHODS
  There were 134 MHD patients enrolled in this cross-sectional study from June to July 2010. Demographics, laboratory data, and excretion capacity of phosphate were recorded. Multivariable linear regression was used to analyze the relationship of serum phosphate and the tubular reabsorption rate of phosphate with other factors.
  
  
  RESULTS
  The median age of the patients was 61.0 years and 47.8% were male. Thirty percent of the patients had high urinary output (>200 ml/d) accompanied by lower serum levels of phosphate, calcium, intact parathyroid hormone, and FGF-23 compared with those with low urine output (≤200 ml/d). The independent predictors of serum phosphate were normalized protein nitrogen appearance, intact parathyroid hormone, and FGF-23 in the low urine output group and female sex and GFR in the high urine output group. The tubular reabsorption rate of phosphate decreased to 50% of the normal level in patients with RRF. Elevated circulating FGF-23 was significantly associated with lower tubular phosphate reabsorption after adjusting for GFR.
  
  
  CONCLUSIONS
  RRF is associated with significant capacity to excrete phosphate in MHD patients and high levels of serum FGF-23 may promote phosphate excretion by remnant nephrons.
authors.affiliation: Division of Nephrology, Huashan Hospital, Shanghai Medical College, Fudan University, Shanghai, China.
authors.forename: Mengjing
authors.initials: M
authors.lastname: Wang
authors.forename: Li
authors.initials: L
authors.lastname: You
authors.forename: Haiming
authors.initials: H
authors.lastname: Li
authors.forename: Yong
authors.initials: Y
authors.lastname: Lin
authors.forename: Zhijie
authors.initials: Z
authors.lastname: Zhang
authors.forename: Chuanming
authors.initials: C
authors.lastname: Hao
authors.forename: Jing
authors.initials: J
authors.lastname: Chen
mesh_terms: D000368:Aged; D003430:Cross-Sectional Studies; D005260:Female; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000097:blood*; D006706:Homeostasis / Q000502:physiology; D006801:Humans; D007015:Hypophosphatemia, Familial / Q000378:metabolism* / Q000401:mortality; D007676:Kidney Failure, Chronic / Q000378:metabolism* / Q000401:mortality / Q000628:therapy*; D007684:Kidney Tubules / Q000378:metabolism; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D008903:Minerals / Q000378:metabolism; D015999:Multivariate Analysis; D010710:Phosphates / Q000097:blood / Q000652:urine*; D006435:Renal Dialysis / Q000401:mortality; D012307:Risk Factors
chemical_list: C000717427:FGF23 protein, human; D008903:Minerals; D010710:Phosphates; D005346:Fibroblast Growth Factors; D000089703:Fibroblast Growth Factor-23