title: Early post-transplantation hypophosphatemia is associated with elevated FGF-23 levels.
abstract: BACKGROUND
  We examined the hypothesis that high FGF-23 levels early after transplantation contribute to the onset of hypophosphatemia, independently of parathyroid hormone (PTH) and other factors regulating phosphate metabolism.
  
  
  METHODS
  We measured serum phosphate levels (sPi), renal tubular reabsorption of Pi (TmPi/GFR), estimated GFR (eGFR), intact PTH (iPTH), calcitriol, intact (int) and C-terminal (Cter) FGF-23, dietary Pi intake and cumulative doses of glucocorticoids in 69 patients 12 days (95% confidence interval, 10-13) after renal transplantation.
  
  
  RESULTS
  Hypophosphatemia was observed in 43 (62%) of the patients 12 days after transplantation. Compared with non-hypophosphatemic subjects, their post-transplantation levels of intact and CterFGF-23 were higher (195 (108-288) vs 48 (40-64) ng/l, P<0.002 for intFGF-23; 205 (116-384) vs 81 (55-124) U/ml, P<0.002, for CterFGF-23). In all subjects, Cter and intFGF-23 correlated inversely with sPi (r=-0.35, P<0.003; -0.35, P<0.003, respectively), and TmPi/GFR (r=-0.50, P<0.001; -0.54, P<0.001, respectively). In multivariate models, sPi and TmPi/GFR were independently associated with FGF-23, iPTH and eGFR. Pre-transplant iPTH levels were significantly higher in patients developing hypophosphatemia after renal transplantation. Pre-transplant levels of FGF-23 were not associated with sPi at the time of transplantation.
  
  
  CONCLUSIONS
  In addition to PTH, elevated FGF-23 may contribute to hypophosphatemia during the early post-renal transplant period.
authors.affiliation: Department of Internal Medicine Service of Transplantation, University Hospitals, Geneva 14, Switzerland. andrea.trombetti@unige.ch
authors.forename: Andrea
authors.initials: A
authors.lastname: Trombetti
authors.forename: Laura
authors.initials: L
authors.lastname: Richert
authors.forename: Karine
authors.initials: K
authors.lastname: Hadaya
authors.forename: Jean-Daniel
authors.initials: JD
authors.lastname: Graf
authors.forename: François R
authors.initials: FR
authors.lastname: Herrmann
authors.forename: Serge L
authors.initials: SL
authors.lastname: Ferrari
authors.forename: Pierre-Yves
authors.initials: PY
authors.lastname: Martin
authors.forename: René
authors.initials: R
authors.lastname: Rizzoli
mesh_terms: D015415:Biomarkers / Q000097:blood; D005260:Female; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000097:blood* / Q000502:physiology; D006084:Graft Rejection / Q000097:blood / Q000175:diagnosis; D006801:Humans; D017674:Hypophosphatemia / Q000097:blood* / Q000150:complications / Q000175:diagnosis; D016030:Kidney Transplantation / Q000009:adverse effects; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000097:blood* / Q000175:diagnosis / Q000209:etiology; D011446:Prospective Studies; D013997:Time Factors
chemical_list: D015415:Biomarkers; C000717427:FGF23 protein, human; D005346:Fibroblast Growth Factors; D000089703:Fibroblast Growth Factor-23