title: Bone and mineral metabolism and fibroblast growth factor 23 levels after kidney donation.
abstract: BACKGROUND
  Living kidney donation offers a unique setting to study changes in phosphate and vitamin D homeostasis attributable to mild isolated decreases in estimated glomerular filtration rate (eGFR).
  
  
  METHODS
  Cross-sectional study.
  
  
  METHODS
  198 living kidney donors and 98 nondonor controls from 9 transplant centers across 3 countries. For donors, median time after donation was 5.3 years. At assessment, donors had a lower eGFR than controls (73 vs 98 mL/min/1.73 m(2)).
  
  
  METHODS
  Living kidney donation (mildly decreased eGFR).
  
  
  RESULTS
  Biochemical markers of chronic kidney disease-mineral and bone disorder.
  
  
  METHODS
  Serum creatinine, total serum calcium, serum and urine inorganic phosphate, plasma intact parathyroid hormone, serum calcidiol and calcitriol, renal fractional excretion of inorganic phosphate, and intact serum fibroblast growth factor 23 (FGF-23).
  
  
  RESULTS
  Serum FGF-23 levels were significantly higher in donors (38.1 vs 29.7 pg/mL; P < 0.001). For every 10-mL/min/1.73 m(2) decrease in eGFR, FGF-23 level was higher by 3.2 (95% CI, 2.0-4.4) pg/mL. Compared with controls, donors showed higher renal tubular fractional excretion of inorganic phosphate (17.8% vs 12.3%; P < 0.001), lower serum phosphate (0.97 vs 1.02 mmol/L; P = 0.03), and lower serum calcitriol values (63 vs 77 pmol/L; P < 0.001). Serum calcium levels were not significantly different between the 2 groups. Plasma intact parathyroid hormone levels were significantly higher in donors (5.7 vs 5.0 pmol/L; P = 0.03), but were not correlated with FGF-23 or calcitriol levels.
  
  
  CONCLUSIONS
  Enrollment of a small proportion of past donors at participating centers; assessment of only postdonation values; unable to assess seasonal variation or other temporal patterns in biochemical markers; assessment of kidney function was based on eGFR, not measured GFR.
  
  
  CONCLUSIONS
  The FGF-23 pathway may be activated in living kidney donors who show early biochemical changes compatible with chronic kidney disease-mineral and bone disorder. Whether these changes influence bone mineral density and fracture rates warrants consideration.
authors.affiliation: Division of Nephrology, University of Western Ontario, London, Ontario, Canada. ann.young@lhsc.on.ca
authors.forename: Ann
authors.initials: A
authors.lastname: Young
authors.forename: Anthony B
authors.initials: AB
authors.lastname: Hodsman
authors.forename: Neil
authors.initials: N
authors.lastname: Boudville
authors.forename: Colin
authors.initials: C
authors.lastname: Geddes
authors.forename: John
authors.initials: J
authors.lastname: Gill
authors.forename: David
authors.initials: D
authors.lastname: Goltzman
authors.forename: Sarbjit Vanita
authors.initials: SV
authors.lastname: Jassal
authors.forename: Scott
authors.initials: S
authors.lastname: Klarenbach
authors.forename: Gregory
authors.initials: G
authors.lastname: Knoll
authors.forename: Norman
authors.initials: N
authors.lastname: Muirhead
authors.forename: G V Ramesh
authors.initials: GV
authors.lastname: Prasad
authors.forename: Darin
authors.initials: D
authors.lastname: Treleaven
authors.forename: Amit X
authors.initials: AX
authors.lastname: Garg
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D015415:Biomarkers / Q000032:analysis / Q000378:metabolism; D001774:Blood Chemical Analysis; D015519:Bone Density / Q000502:physiology*; D016001:Confidence Intervals; D003404:Creatinine / Q000097:blood; D003430:Cross-Sectional Studies; D005260:Female; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000032:analysis / Q000378:metabolism*; D005598:Fractures, Spontaneous / Q000209:etiology / Q000503:physiopathology; D005919:Glomerular Filtration Rate; D006801:Humans; D016030:Kidney Transplantation / Q000379:methods*; D019520:Living Donors; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009392:Nephrectomy / Q000009:adverse effects* / Q000379:methods; D010024:Osteoporosis / Q000209:etiology / Q000503:physiopathology; D011379:Prognosis; D012016:Reference Values; D051437:Renal Insufficiency / Q000209:etiology* / Q000503:physiopathology; D012189:Retrospective Studies; D018570:Risk Assessment; D012737:Sex Factors; D055815:Young Adult
chemical_list: D015415:Biomarkers; C000717427:FGF23 protein, human; D005346:Fibroblast Growth Factors; D000089703:Fibroblast Growth Factor-23; D003404:Creatinine