title: Important non-disease-related determinants of exhaled nitric oxide levels in mild asthma - results from the Swedish GA(2) LEN study.
abstract: Fractional exhaled nitric oxide (FeNO) has a potential clinical role in asthma management. Constitutive factors such as age, height and gender, as well as individual characteristics, such as IgE sensitization and smoking, affect the levels of FeNO in population-based studies. However, their effect on FeNO in subjects with asthma has been scarcely studied.
  
  
  
  To study the effects on FeNO of these commonly regarded determinants, as demonstrated in healthy subjects, as well as menarche age and parental smoking, in a population of asthmatics.
  
  
  
  Fractional exhaled nitric oxide was measured in 557 subjects with asthma from the Swedish GA(2) LEN study. Allergic sensitization was assessed by skin prick tests to most common aeroallergens. Upper airway comorbidities, smoking habits, smoking exposure during childhood and hormonal status (for women) were questionnaire-assessed.
  
  
  
  Male gender (P < 0.001), greater height (P < 0.001) and sensitization to both perennial allergens and pollen (P < 0.001) are related to higher FeNO levels. Current smoking (P < 0.001) and having both parents smoking during childhood, vs. having neither (P < 0.001) or only one parent smoking (P = 0.002), are related to lower FeNO. Women with menarche between 9 and 11 years of age had lower FeNO than those with menarche between 12 and 14 years of age (P = 0.03) or 15 and 17 years of age (P = 0.003).
  
  
  
  Interpreting FeNO levels in clinical practice is complex, and constitutional determinants, as well as smoking and IgE sensitisation, are of importance in asthmatic subjects and should be accounted for when interpreting FeNO levels. Furthermore, menarche age and parental smoking during childhood and their effects on lowering FeNO deserve further studies.
authors.affiliation: Department of Medical Sciences: Lung- allergy- and sleep research, Uppsala University, Uppsala, Sweden.
authors.forename: N
authors.initials: N
authors.lastname: Al-Shamkhi
authors.affiliation: Department of Women's and Children's Health, Uppsala University, Uppsala, Sweden.
authors.forename: K
authors.initials: K
authors.lastname: Alving
authors.affiliation: Experimental Asthma and Allergy Research Unit, Institute of Environmental Medicine, Karolinska Institute, Stockholm, Sweden.
authors.forename: S E
authors.initials: SE
authors.lastname: Dahlen
authors.affiliation: Department of Women's and Children's Health, Karolinska Institute, Stockholm, Sweden.
authors.forename: G
authors.initials: G
authors.lastname: Hedlin
authors.affiliation: Experimental Asthma and Allergy Research Unit, Institute of Environmental Medicine, Karolinska Institute, Stockholm, Sweden.
authors.forename: R
authors.initials: R
authors.lastname: Middelveld
authors.affiliation: Department of Internal Medicine and Clinical Nutrition, Krefting Research Centre, University of Gothenburg, Gothenburg, Sweden.
authors.forename: A
authors.initials: A
authors.lastname: Bjerg
authors.affiliation: Department of Internal Medicine and Clinical Nutrition, Krefting Research Centre, University of Gothenburg, Gothenburg, Sweden.
authors.forename: L
authors.initials: L
authors.lastname: Ekerljung
authors.affiliation: Section of Occupational and Environmental Medicine, Department of Public Health and Community Medicine, Institute of Medicine, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden.
authors.forename: A C
authors.initials: AC
authors.lastname: Olin
authors.affiliation: Department of Public Health and Clinical Medicine, Occupational and Environmental Medicine, University of Umeå, Umeå, Sweden.
authors.forename: J
authors.initials: J
authors.lastname: Sommar
authors.affiliation: Department of Public Health and Clinical Medicine, Occupational and Environmental Medicine, University of Umeå, Umeå, Sweden.
authors.forename: B
authors.initials: B
authors.lastname: Forsberg
authors.affiliation: Department of Medical Sciences: Lung- allergy- and sleep research, Uppsala University, Uppsala, Sweden.
authors.forename: C
authors.initials: C
authors.lastname: Janson
authors.affiliation: Department of Medical Sciences: Clinical Physiology, Uppsala University, Uppsala, Sweden.
authors.forename: A
authors.initials: A
authors.lastname: Malinovschi
mesh_terms: D000328:Adult; D001249:Asthma / Q000175:diagnosis / Q000453:epidemiology* / Q000276:immunology / Q000378:metabolism*; D015415:Biomarkers; D001837:Body Weights and Measures; D015897:Comorbidity; D045853:Exhalation; D005260:Female; D012739:Gonadal Steroid Hormones / Q000378:metabolism; D006801:Humans; D007073:Immunoglobulin E / Q000276:immunology; D008297:Male; D008597:Menstrual Cycle; D008875:Middle Aged; D009569:Nitric Oxide / Q000378:metabolism*; D011058:Pollen; D012129:Respiratory Function Tests; D012307:Risk Factors; D012720:Severity of Illness Index; D012882:Skin Tests; D013147:Spirometry; D013548:Sweden / Q000453:epidemiology
chemical_list: D015415:Biomarkers; D012739:Gonadal Steroid Hormones; D009569:Nitric Oxide; D007073:Immunoglobulin E
keywords: GA
  2
  LEN; asthma; determinants; exhaled nitric oxide; menarche; parental smoking