title: Low-grade inflammation is associated with lower haemoglobin levels in healthy individuals: results from the Danish blood donor study.
abstract: OBJECTIVE
  Chronic inflammation can lead to anaemia of chronic disease due to the sequestration of iron caused by inflammatory cytokines and the protein hepcidin. However, the effect of low-grade inflammation (LGI) on haemoglobin among healthy individuals is not known. This study examines the effect of LGI on haemoglobin among Danish blood donors.
  
  
  METHODS
  We performed multivariable linear regression to assess the effect of LGI (i.e. high-sensitivity C-reactive protein above 3 mg/l but below 10 mg/l) on haemoglobin in 17 322 Danish blood donors. We also performed multivariable logistic regression to evaluate the effect of LGI on the risk of having low haemoglobin (below the 10th percentile among men and women, respectively). We adjusted for donation activity, age, sex, low ferritin, oral contraceptives and menopause. All analyses were stratified by current smoking status.
  
  
  RESULTS
  LGI was associated with lower haemoglobin (0·08 mm lower [0·12 g/dl], 95% confidence interval (CI): -0·11-0·05) and increased risk of low haemoglobin (OR = 1·22, 95% CI: 1·05-1·43) in non-smokers. Conversely, LGI was associated with higher haemoglobin in smokers (0·12 mm [0·19 g/dl], 95% CI: 0·06-0·18).
  
  
  CONCLUSIONS
  In this first study of LGI and haemoglobin in healthy individuals, there was a negative association between LGI and haemoglobin in non-smokers. The association was positive in smokers, probably because smoking leads to both increased inflammation and increased haemoglobin through CO exposure.
authors.affiliation: Department of Clinical Immunology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: S R
authors.initials: SR
authors.lastname: Kotzé
authors.affiliation: Department of Clinical Immunology, Naestved Hospital, Naestved, Denmark.
authors.forename: O B
authors.initials: OB
authors.lastname: Pedersen
authors.affiliation: Department of Clinical Immunology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: M S
authors.initials: MS
authors.lastname: Petersen
authors.affiliation: Department of Clinical Immunology, Copenhagen University Hospital, Copenhagen, Denmark.
authors.forename: E
authors.initials: E
authors.lastname: Sørensen
authors.affiliation: Department of Clinical Immunology, Copenhagen University Hospital, Copenhagen, Denmark.
authors.forename: L W
authors.initials: LW
authors.lastname: Thørner
authors.affiliation: Department of Clinical Immunology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: C J
authors.initials: CJ
authors.lastname: Sørensen
authors.affiliation: Department of Clinical Immunology, Copenhagen University Hospital, Copenhagen, Denmark.
authors.forename: A S
authors.initials: AS
authors.lastname: Rigas
authors.affiliation: Department of Epidemiological Research, Statens Serum Institut, Copenhagen, Denmark.
authors.forename: H
authors.initials: H
authors.lastname: Hjalgrim
authors.affiliation: Department of Epidemiological Research, Statens Serum Institut, Copenhagen, Denmark.
authors.forename: K
authors.initials: K
authors.lastname: Rostgaard
authors.affiliation: Department of Clinical Immunology, Copenhagen University Hospital, Copenhagen, Denmark.
authors.forename: H
authors.initials: H
authors.lastname: Ullum
authors.affiliation: Department of Clinical Immunology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: C
authors.initials: C
authors.lastname: Erikstrup
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001782:Blood Donors; D002097:C-Reactive Protein / Q000032:analysis; D005260:Female; D006454:Hemoglobins / Q000032:analysis*; D006801:Humans; D007249:Inflammation; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009426:Netherlands; D012907:Smoking; D011795:Surveys and Questionnaires; D055815:Young Adult
chemical_list: D006454:Hemoglobins; D002097:C-Reactive Protein
keywords: C-reactive protein; Low-grade inflammation; blood donation; epidemiology; haemoglobin