title: Fibroblast growth factor 23 (FGF23) and early chronic kidney disease in the elderly.
abstract: BACKGROUND
  Better biomarkers of CKD reflecting responses to decreased glomerular filtration rate (GFR) are needed. We determined the value of estimated GFR (eGFR) as a threshold for the increase of plasma cFGF23 (C-terminal) and intact fibroblast growth factor-23 (iFGF23) (intact) concentrations in the course of chronic kidney disease (CKD) and compared this eGFR value with values related to increased serum intact parathyroid hormone (iPTH) or phosphorus concentrations in an elderly population.
  
  
  METHODS
  We measured plasma iFGF23, cFGF23, serum phosphorus, calcium, albumin, creatinine, urea, cystatin C, iPTH and vitamin 25-OH-D3 in 3780 population-based study participants aged ≥ 65 years.
  
  
  RESULTS
  Serum phosphorus concentrations hardly increased until mean eGFR reached 47.3 ± 4.7 mL/min/1.73 m(2) but then increased exponentially. Similarly, both iPTH and iFGF23 increased slightly in early CKD but then increased exponentially when eGFR reached 55.0 ± 4.2 mL/min/1.73 m(2) for iPTH and 51.6 ± 5.7 mL/min/1.73 m(2) for iFGF23. The departure point for exponential increases in cFGF23 preceded those for iPTH and iFGF23 and occurred at a mean eGFR of 57.7 ± 7.8 mL/min/1.73 m(2). The prevalence of increased iFGF23 occurred at a remarkably higher eGFR value than that of cFGF23 across the CKD stages.
  
  
  CONCLUSIONS
  The increase in cFGF23 preceded both the increase in iPTH and iFGF23 as eGFR declined. Increased plasma iFGF23 level did not precede the rise in serum iPTH concentrations and did not occur before stage-3 CKD in elderly persons. However, cFGF23 was not an early marker of CKD in the elderly subjects.
authors.affiliation: Pathophysiology Unit, Department of Pathophysiology, Medical University of Silesia, Katowice, Poland Department of Nephrology, Endocrinology and Metabolic Diseases, Medical University of Silesia, Katowice, Poland.
authors.forename: Jerzy
authors.initials: J
authors.lastname: Chudek
authors.affiliation: Health Promotion and Obesity Management Unit, Department of Pathophysiology, Medical University of Silesia, Katowice, Poland.
authors.forename: Piotr
authors.initials: P
authors.lastname: Kocełak
authors.affiliation: Division of Statistics in Sosnowiec, Medical University of Silesia, Katowice, Poland.
authors.forename: Aleksander
authors.initials: A
authors.lastname: Owczarek
authors.affiliation: Pathophysiology Unit, Department of Pathophysiology, Medical University of Silesia, Katowice, Poland.
authors.forename: Maria
authors.initials: M
authors.lastname: Bożentowicz-Wikarek
authors.affiliation: International Institute of Molecular and Cell Biology, Warsaw, Poland.
authors.forename: Małgorzata
authors.initials: M
authors.lastname: Mossakowska
authors.affiliation: Health Promotion and Obesity Management Unit, Department of Pathophysiology, Medical University of Silesia, Katowice, Poland.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Olszanecka-Glinianowicz
authors.affiliation: Department of Nephrology, Endocrinology and Metabolic Diseases, Medical University of Silesia, Katowice, Poland.
authors.forename: Andrzej
authors.initials: A
authors.lastname: Wiecek
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood; D018450:Disease Progression; D005260:Female; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000097:blood*; D005919:Glomerular Filtration Rate / Q000502:physiology; D006801:Humans; D007668:Kidney; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood; D010758:Phosphorus / Q000097:blood; D051436:Renal Insufficiency, Chronic / Q000097:blood*
chemical_list: D015415:Biomarkers; C000717427:FGF23 protein, human; D010281:Parathyroid Hormone; D010758:Phosphorus; D005346:Fibroblast Growth Factors; D000089703:Fibroblast Growth Factor-23
keywords: chronic kidney disease; elderly population; fibroblast growth factor 23