title: Iron status is associated with asthma and lung function in US women.
abstract: BACKGROUND
  Asthma and iron deficiency are common conditions. Whether iron status affects the risk of asthma is unclear.
  
  
  OBJECTIVE
  To determine the relationship between iron status and asthma, lung function, and pulmonary inflammation.
  
  
  METHODS
  Relationships between measures of iron status (serum ferritin, serum soluble transferrin receptor (sTfR), and sTfR/log10ferritin (sTfR-F Index)) and asthma, lung function, and pulmonary inflammation were examined in women 20-49 years in the National Health and Nutrition Examination Survey. Logistic, linear, and quadratic regression models accounting for the survey design of NHANES were used to evaluate associations between iron status and asthma-related outcomes and were adjusted for race/ethnicity, age, smoking status, income, and BMI.
  
  
  RESULTS
  Approximately 16% reported a lifetime history of asthma, 9% reported current asthma, and 5% reported a recent asthma episode/attack (n = 2906). Increased ferritin (iron stores) was associated with decreased odds of lifetime asthma, current asthma, and asthma attacks/episodes in the range of ferritin linearly correlated with iron stores (20-300ng/ml). The highest quintile of ferritin (>76 ng/ml) was also associated with a decreased odds of asthma. Ferritin levels were not associated with FEV1. Increased values of the sTfR-F Index and sTfR, indicating lower body iron and higher tissue iron need, respectively, were associated with decreased FEV1, but neither was associated with asthma. None of the iron indices were associated with FeNO.
  
  
  CONCLUSIONS
  In US women, higher iron stores were inversely associated with asthma and lower body iron and higher tissue iron need were associated with lower lung function. Together, these findings suggest that iron status may play a role in asthma and lung function in US women.
authors.affiliation: Johns Hopkins University School of Medicine, Division of Pulmonary and Critical Care Medicine, Baltimore, Maryland, United States of America.
authors.forename: Emily P
authors.initials: EP
authors.lastname: Brigham
authors.affiliation: Johns Hopkins University School of Medicine, Division of Pulmonary and Critical Care Medicine, Baltimore, Maryland, United States of America; Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland, United States of America.
authors.forename: Meredith C
authors.initials: MC
authors.lastname: McCormack
authors.affiliation: Johns Hopkins University School of Medicine, Division of Pediatric Hematology, Baltimore, Maryland, United States of America.
authors.forename: Clifford M
authors.initials: CM
authors.lastname: Takemoto
authors.affiliation: Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland, United States of America; Johns Hopkins University School of Medicine, Division of Pediatric Allergy and Immunology, Baltimore, Maryland, United States of America.
authors.forename: Elizabeth C
authors.initials: EC
authors.lastname: Matsui
mesh_terms: D000293:Adolescent; D000328:Adult; D000740:Anemia / Q000150:complications; D001249:Asthma / Q000150:complications / Q000453:epidemiology* / Q000378:metabolism* / Q000503:physiopathology; D002648:Child; D005260:Female; D006306:Health Surveys; D006801:Humans; D007501:Iron / Q000378:metabolism*; D008875:Middle Aged; D009749:Nutrition Surveys; D011014:Pneumonia / Q000150:complications / Q000378:metabolism; D012129:Respiratory Function Tests; D012306:Risk; D014481:United States; D055815:Young Adult
chemical_list: D007501:Iron