title: Associations of fibroblast growth factor-23 with markers of inflammation, insulin resistance and obesity in adults.
abstract: BACKGROUND
  Elevated fibroblast growth factor-23 (FGF23) is an established marker of cardiovascular disease. The underlying reason(s) for the rise accompanying cardiovascular health decline are unclear. Prior studies have shown that FGF23 concentrations are associated with markers of inflammation and insulin resistance but they have been limited by a focus on persons with chronic kidney disease (CKD) and lack of race and sex diversity. The objective of this study was to examine the associations of FGF23 and markers of inflammation, insulin resistance, and anthropometrics in a large cohort of community-dwelling adults.
  
  
  METHODS
  Associations of FGF23 with markers of inflammation [interleukin-6 (IL-6), IL-10, high sensitivity-CRP (hsCRP)], insulin utilization [resistin, adiponectin, homeostatic model assessment of insulin resistance (HOMA-IR)] and anthropometrics [BMI and waist circumference (WC)] were examined cross-sectionally in a 1,040 participants randomly selected from the Reason for Geographic and Racial Differences in Stroke (REGARDS) Study, a national study of black and white adults ≥45 years. Effect modification by race and CKD status was tested, and stratified models were analyzed accordingly.
  
  
  RESULTS
  Median FGF23 concentration was 69.6 RU/ml (IQR: 53.2, 102.7). Higher quartiles of FGF23 were associated with higher mean concentrations of IL-6, IL-10, hsCRP and resistin (Ptrend<0.001 for all). There were no significant differences in HOMA-IR, adiponectin concentrations, BMI, or WC across FGF23 quartiles in the crude analyses. CKD significantly modified the relationships between FGF23 and inflammatory markers, HOMA-IR, BMI and WC (P ≤ 0.01 for all). In linear regression models adjusted for sociodemographic and clinical variables, FGF23 was positively associated with IL-6, hsCRP, IL-10, HOMA-IR, BMI and WC in individuals without CKD, but not among individuals with CKD. Additionally, FGF23 was positively associated with resistin irrespective of CKD status.
  
  
  CONCLUSIONS
  Elevated FGF23 concentrations may be considered a biomarker for decline in metabolic function among individuals with normal kidney function.
authors: Department of Pediatrics, Children's Hospital of Alabama, University of Alabama at Birmingham, Birmingham, Alabama, United States of America.
authors: Lynae J
authors: LJ
authors: Hanks
authors: Department of Pediatrics, Children's Hospital of Alabama, University of Alabama at Birmingham, Birmingham, Alabama, United States of America.
authors: Krista
authors: K
authors: Casazza
authors: Department of Biostatistics, University of Alabama at Birmingham, Birmingham, Alabama, United States of America.
authors: Suzanne E
authors: SE
authors: Judd
authors: Pathology and Laboratory Medicine, University of Vermont College of Medicine, Colchester, Vermont, United States of America.
authors: Nancy S
authors: NS
authors: Jenny
authors: Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States of America.
authors: Orlando M
authors: OM
authors: Gutiérrez
mesh_terms: D000328:Adult; D000368:Aged; D000886:Anthropometry; D015415:Biomarkers / Q000097:blood*; D005260:Female; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000097:blood*; D006801:Humans; D007249:Inflammation / Q000097:blood* / Q000150:complications; D007333:Insulin Resistance; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009765:Obesity / Q000097:blood* / Q000150:complications; D051436:Renal Insufficiency, Chronic / Q000097:blood / Q000150:complications
chemical_list: D015415:Biomarkers; C000717427:FGF23 protein, human; D005346:Fibroblast Growth Factors; D000089703:Fibroblast Growth Factor-23