title: Racial differences in markers of mineral metabolism in advanced chronic kidney disease.
abstract: OBJECTIVE
  This study examined differences in the concentration of markers of mineral metabolism across race in patients with advanced CKD not requiring dialysis and ESRD.
  
  
  METHODS
  Concentrations of 25-hydroxyvitamin D (25(OH)D), 1,25-dihydroxyvitamin D (1,25(OH)(2)D), intact parathyroid hormone (iPTH), and fibroblast growth factor 23 (FGF-23) were measured in stored plasma samples of 1497 patients with advanced CKD not yet on dialysis and ESRD who participated in the Homocysteine in Kidney and End Stage Renal Disease study. Linear regression models were used to examine the relationship between race and 25(OH)D, 1,25(OH)(2)D, iPTH, and FGF-23 concentrations.
  
  
  RESULTS
  Non-Hispanic white patients comprised 58% of the cohort, whereas non-Hispanic blacks comprised 42%. Median (interquartile range) FGF-23 concentrations were lower in blacks compared with whites with CKD (323 [181-655] versus 431 [232-1026] RU/ml; P<0.001) but not in ESRD. In adjusted linear regression models, blacks with CKD not requiring dialysis had significantly lower plasma FGF-23 concentrations (difference, -159; 95% confidence interval, -205 to -106; P<0.001) compared with whites, independent of plasma 25(OH)D, 1,25(OH)(2)D, and iPTH concentrations. This difference was not observed in the ESRD group. The magnitude of correlation for the relationships between 1,25(OH)(2)D with iPTH, FGF-23 with 1,25(OH)(2)D, and FGF-23 with iPTH were stronger among blacks than whites with CKD not requiring dialysis.
  
  
  CONCLUSIONS
  In advanced CKD not requiring dialysis, blacks have lower FGF-23 concentrations than whites. Blacks with CKD and ESRD have lower 25(OH)D and higher iPTH compared with whites, independent of FGF-23 concentrations.
authors.affiliation: Division of Renal Diseases and Hypertension, University of Colorado School of Medicine, Aurora, USA.
authors.forename: Anna
authors.initials: A
authors.lastname: Jovanovich
authors.forename: Michel
authors.initials: M
authors.lastname: Chonchol
authors.forename: Alfred K
authors.initials: AK
authors.lastname: Cheung
authors.forename: James S
authors.initials: JS
authors.lastname: Kaufman
authors.forename: Tom
authors.initials: T
authors.lastname: Greene
authors.forename: William L
authors.initials: WL
authors.lastname: Roberts
authors.forename: Gerard
authors.initials: G
authors.lastname: Smits
authors.forename: Jessica
authors.initials: J
authors.lastname: Kendrick
mesh_terms: D001741:Black or African American / Q000706:statistics & numerical data*; D000368:Aged; D015415:Biomarkers / Q000097:blood; D001842:Bone and Bones / Q000378:metabolism*; D016009:Chi-Square Distribution; D002908:Chronic Disease; D003430:Cross-Sectional Studies; D005260:Female; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000097:blood; D006801:Humans; D007674:Kidney Diseases / Q000097:blood* / Q000208:ethnology* / Q000628:therapy; D007676:Kidney Failure, Chronic / Q000097:blood* / Q000208:ethnology* / Q000628:therapy; D016014:Linear Models; D008297:Male; D008659:Metabolic Diseases / Q000097:blood* / Q000208:ethnology* / Q000628:therapy; D008875:Middle Aged; D015999:Multivariate Analysis; D010281:Parathyroid Hormone / Q000097:blood; D011446:Prospective Studies; D014481:United States / Q000453:epidemiology; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood; D044465:White People / Q000706:statistics & numerical data*
chemical_list: D015415:Biomarkers; C000717427:FGF23 protein, human; C470125:PTH protein, human; D010281:Parathyroid Hormone; D014807:Vitamin D; D005346:Fibroblast Growth Factors; C097949:1,25-dihydroxyvitamin D; D000089703:Fibroblast Growth Factor-23; C104450:25-hydroxyvitamin D