title: Utility of Exhaled Nitric Oxide Fraction for the Diagnosis of Hypersensitivity Pneumonitis.
abstract: BACKGROUND
  There is very little evidence of the utility of the exhaled fraction of NO (FeNO) for the diagnosis of interstitial lung disease and nearly all of it is related with connective tissue disease. Some authors have suggested that in patients with hypersensitivity pneumonitis (HP), evolution to pulmonary fibrosis may be mediated by a Th2 mechanism, which could redound in a potential utility of FeNO. The aim of this study was to investigate the values of FeNO before and after antigenic exposure with the specific inhalation challenge (SIC) and to analyze its potential utility for the diagnosis of HP.
  
  
  METHODS
  It was a prospective, cross-sectional study of all patients older than 18 years referred to our center for suspected chronic HP between May 2012 and May 2014 and who underwent a SIC. FeNO was collected before and after SIC.
  
  
  RESULTS
  The study sample comprised 25 patients. Eleven were diagnosed with chronic HP; six had been exposed to avian proteins and five to fungal agents. Of these 11 patients, seven had positive SICs. In the 14 patients with diagnoses other than HP, all the SICs were negative. No significant differences in baseline characteristics were observed according to HP diagnosis, except in the BAL lymphocyte count. No differences were found after the test in patients diagnosed with HP; nor were there differences in baseline FeNO in patients diagnosed with HP and those who received alternative diagnoses.
  
  
  CONCLUSIONS
  The results suggest that FeNO measurement is not useful for the diagnosis of chronic HP.
authors.affiliation: Respiratory Service, Department of Medicine, Vall d'Hebron University Hospital, Autonomous University of Barcelona, Passeig Vall d'Hebron, 119, 08035, Barcelona, Catalonia, Spain.|CIBER Enfermedades Respiratorias (Ciberes), Barcelona, Spain.
authors.forename: I
authors.initials: I
authors.lastname: Ojanguren
authors.affiliation: Respiratory Service, Department of Medicine, Vall d'Hebron University Hospital, Autonomous University of Barcelona, Passeig Vall d'Hebron, 119, 08035, Barcelona, Catalonia, Spain. mj.cruz@vhir.org.|CIBER Enfermedades Respiratorias (Ciberes), Barcelona, Spain. mj.cruz@vhir.org.
authors.forename: M J
authors.initials: MJ
authors.lastname: Cruz
authors.affiliation: Respiratory Service, Department of Medicine, Vall d'Hebron University Hospital, Autonomous University of Barcelona, Passeig Vall d'Hebron, 119, 08035, Barcelona, Catalonia, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Villar
authors.affiliation: Respiratory Service, Department of Medicine, Vall d'Hebron University Hospital, Autonomous University of Barcelona, Passeig Vall d'Hebron, 119, 08035, Barcelona, Catalonia, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Barrecheguren
authors.affiliation: Respiratory Service, Department of Medicine, Vall d'Hebron University Hospital, Autonomous University of Barcelona, Passeig Vall d'Hebron, 119, 08035, Barcelona, Catalonia, Spain.|CIBER Enfermedades Respiratorias (Ciberes), Barcelona, Spain.
authors.forename: F
authors.initials: F
authors.lastname: Morell
authors.affiliation: Respiratory Service, Department of Medicine, Vall d'Hebron University Hospital, Autonomous University of Barcelona, Passeig Vall d'Hebron, 119, 08035, Barcelona, Catalonia, Spain.|CIBER Enfermedades Respiratorias (Ciberes), Barcelona, Spain.|Department of Cell Biology, Physiology and Immunology, Autonomous University of Barcelona, Barcelona, Catalonia, Spain.
authors.forename: X
authors.initials: X
authors.lastname: Muñoz
mesh_terms: D000328:Adult; D000368:Aged; D000542:Alveolitis, Extrinsic Allergic / Q000175:diagnosis* / Q000503:physiopathology; D001716:Bird Fancier's Lung / Q000175:diagnosis / Q000503:physiopathology; D001944:Breath Tests; D001985:Bronchial Provocation Tests; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology; D002248:Carbon Monoxide; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D018655:Lymphocyte Count; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000032:analysis*; D011446:Prospective Studies; D011653:Pulmonary Diffusing Capacity; D014797:Vital Capacity
chemical_list: D009569:Nitric Oxide; D002248:Carbon Monoxide
keywords: Inflammation; Interstitial lung disease; Pulmonary fibrosis; Specific inhalation challenge