title: Non-transferrin-bound iron and risk of coronary heart disease in postmenopausal women.
abstract: BACKGROUND
  Epidemiological studies aimed at correlating coronary heart disease (CHD) with serum ferritin levels have thus far yielded inconsistent results. We hypothesized that a labile iron component associated with non-transferrin-bound iron (NTBI) that appears in individuals with overt or cryptic iron overload might be more suitable for establishing correlations with CHD.
  
  
  RESULTS
  We investigated the relation of NTBI, serum iron, transferrin saturation, and serum ferritin with risk of CHD and acute myocardial infarction (AMI). The cohort used comprised a population-based sample of 11 471 postmenopausal women aged 49 to 70 years at enrollment in 1993 to 1997. During a median follow-up of 4.3 years (quartile limits Q1 to Q3: 3.3 to 5.4), 185 CHD events were identified, including 66 AMI events. We conducted a case-cohort study using all CHD cases and a random sample from the baseline cohort (n=1134). A weighted Cox proportional hazards model was used to estimate hazard ratios for tertiles of iron variables in relation to CHD and AMI. Adjusted hazard ratios of women in the highest NTBI tertile (range 0.38 to 3.51) compared with the lowest (range -2.06 to -0.32) were 0.84 (95% confidence interval 0.61 to 1.16) for CHD and 0.47 (95% confidence interval 0.31 to 0.71) for AMI. The results were similar for serum iron, transferrin saturation, and serum ferritin.
  
  
  CONCLUSIONS
  Our results show no excess risk of CHD or AMI within the highest NTBI tertile compared with the lowest but rather seem to demonstrate a decreased risk. Additional studies are warranted to confirm our findings.
authors.affiliation: Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Daphne L
authors.initials: DL
authors.lastname: van der A
authors.forename: Joannes J M
authors.initials: JJ
authors.lastname: Marx
authors.forename: Diederick E
authors.initials: DE
authors.lastname: Grobbee
authors.forename: Marjolein H
authors.initials: MH
authors.lastname: Kamphuis
authors.forename: Niki A
authors.initials: NA
authors.lastname: Georgiou
authors.forename: J Henny
authors.initials: JH
authors.lastname: van Kats-Renaud
authors.forename: William
authors.initials: W
authors.lastname: Breuer
authors.forename: Z Ioav
authors.initials: ZI
authors.lastname: Cabantchik
authors.forename: Mark
authors.initials: M
authors.lastname: Roest
authors.forename: Hieronymus A M
authors.initials: HA
authors.lastname: Voorbij
authors.forename: Yvonne T
authors.initials: YT
authors.lastname: van der Schouw
mesh_terms: D000368:Aged; D002097:C-Reactive Protein / Q000032:analysis; D016022:Case-Control Studies; D003327:Coronary Disease / Q000097:blood / Q000209:etiology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007501:Iron / Q000097:blood*; D008875:Middle Aged; D017698:Postmenopause / Q000097:blood*; D016016:Proportional Hazards Models; D014168:Transferrin / Q000032:analysis
chemical_list: D014168:Transferrin; D002097:C-Reactive Protein; D007501:Iron