title: FGF23 and mineral metabolism in the early post-renal transplantation period.
abstract: BACKGROUND
  The relationship between fibroblast growth factor 23 (FGF23) and vitamin D production and catabolism post-renal transplantation has not been characterized.
  
  
  METHODS
  Circulating creatinine, calcium, phosphorus, albumin, parathyroid hormone, FGF23, and 1,25(OH)2 vitamin D (calcitriol) values were obtained pre-transplantation, daily post-operatively for 5 days, and at 6 months post-transplantation in 44 patients aged 16.4 ± 0.4 years undergoing renal transplantation at UCLA from 1 August 2005 through to 30 April 2007. 25(OH) Vitamin D and 24,25(OH)2 vitamin D concentrations were obtained at baseline and on post-operative days 5 and 180, and urinary concentrations of creatinine, phosphorus, and FGF23 were measured on post-operative days 1, 3, 5, and 180.
  
  
  RESULTS
  Circulating phosphate concentrations declined more rapidly and the fractional excretion of phosphorus was higher in the first week post-transplantation in subjects with higher FGF23 values. Fractional excretion of FGF23 was low at all time-points. Circulating 1,25(OH)2 vitamin D levels rose more rapidly and were consistently higher in patients with lower FGF23 values; however, 25(OH) vitamin D and 24,25(OH)2 vitamin D values were unrelated to FGF23 concentrations.
  
  
  CONCLUSIONS
  Inhibition of renal 1α-hydroxylase, rather than stimulation of 24-hydroxylase, may primarily contribute to the relationship between FGF23 values and calcitriol. The rapid decline in FGF23 levels post-transplantation in our patient cohort was not mediated solely by the filtration of intact FGF23 by the new kidney.
authors.affiliation: Department of Pediatrics, David Geffen School of Medicine at UCLA, A2-383 MDCC, 650 Charles Young Drive, Los Angeles, 90095, CA, USA, kwesseling@mednet.ucla.edu.
authors.forename: Katherine
authors.initials: K
authors.lastname: Wesseling-Perry
authors.forename: Renata C
authors.initials: RC
authors.lastname: Pereira
authors.forename: Eileen
authors.initials: E
authors.lastname: Tsai
authors.forename: Robert
authors.initials: R
authors.lastname: Ettenger
authors.forename: Harald
authors.initials: H
authors.lastname: Jüppner
authors.forename: Isidro B
authors.initials: IB
authors.lastname: Salusky
mesh_terms: D000293:Adolescent; D015153:Blotting, Western; D002117:Calcitriol / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002648:Child; D003404:Creatinine / Q000378:metabolism; D004872:Ergocalciferols / Q000378:metabolism; D005260:Female; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000378:metabolism* / Q000652:urine; D006801:Humans; D007676:Kidney Failure, Chronic / Q000209:etiology / Q000601:surgery; D016030:Kidney Transplantation; D008297:Male; D008903:Minerals / Q000378:metabolism*; D010281:Parathyroid Hormone / Q000378:metabolism; D010710:Phosphates / Q000652:urine; D010758:Phosphorus / Q000378:metabolism; D055815:Young Adult
chemical_list: D004872:Ergocalciferols; C000717427:FGF23 protein, human; D008903:Minerals; D010281:Parathyroid Hormone; D010710:Phosphates; D010758:Phosphorus; C003564:1,25-dihydroxyergocalciferol; D005346:Fibroblast Growth Factors; D000089703:Fibroblast Growth Factor-23; D003404:Creatinine; D002117:Calcitriol; D002118:Calcium