title: Comparison of biomarkers in exhaled breath condensate and bronchoalveolar lavage.
abstract: BACKGROUND
  Exhaled breath condensate (EBC) is increasingly studied as a noninvasive research method of sampling the lungs, measuring several biomarkers. The exact site of origin of substances measured in EBC is unknown, as is the clinical applicability of the technique. Special techniques might be needed to measure EBC biomarkers.
  
  
  OBJECTIVE
  To assess biomarker concentrations in clinical disease and investigate the site of origin of EBC, we compared EBC and bronchoalveolar lavage (BAL) biomarkers in 49 patients undergoing bronchoscopy for clinical indications.
  
  
  METHODS
  We measured exhaled nitric oxide, 8-isoprostane, hydrogen peroxide, total nitrogen oxides, pH, total protein, and phospholipid (n = 33) and keratin (n = 15) to assess alveolar and mucinous compartments, respectively. EBC was collected over 10 min using a refrigerated condenser according to European Respiratory Society/American Thoracic Society recommendations, and BAL performed immediately thereafter.
  
  
  RESULTS
  8-Isoprostane, nitrogen oxides, and pH were significantly higher in EBC than in BAL (3.845 vs. 0.027 ng/ml, 28.4 vs. 3.8 microM, and 7.35 vs. 6.4, respectively; p < 0.001). Hydrogen peroxide showed no difference between EBC and BAL (17.5 vs. 20.6 microM, p = not significant), whereas protein was significantly higher in BAL (33.8 vs. 183.2 microg/ml, p < 0.001). Total phospholipid was also higher in EBC, but keratin showed no difference. No significant correlation was found between EBC and BAL for any of the biomarkers evaluated either before or after correction for dilution.
  
  
  CONCLUSIONS
  In clinical disease, markers of inflammation and oxidative stress are easily measurable in EBC using standard laboratory techniques and EBC is readily obtained. However, EBC and BAL markers do not correlate.
authors.affiliation: Department of Thoracic Medicine, St. Vincent's Hospital, Victoria Street, Darlinghurst, Sydney, Australia.
authors.forename: Abigail S
authors.initials: AS
authors.lastname: Jackson
authors.forename: Alessandra
authors.initials: A
authors.lastname: Sandrini
authors.forename: Charlotte
authors.initials: C
authors.lastname: Campbell
authors.forename: Sharron
authors.initials: S
authors.lastname: Chow
authors.forename: Paul S
authors.initials: PS
authors.lastname: Thomas
authors.forename: Deborah H
authors.initials: DH
authors.lastname: Yates
mesh_terms: D015415:Biomarkers / Q000032:analysis; D001944:Breath Tests / Q000379:methods*; D018893:Bronchoalveolar Lavage; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry; D015237:Dinoprost / Q000031:analogs & derivatives / Q000032:analysis; D045853:Exhalation; D005260:Female; D006801:Humans; D006861:Hydrogen Peroxide / Q000032:analysis; D007249:Inflammation / Q000175:diagnosis; D007633:Keratins / Q000032:analysis; D008171:Lung Diseases / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000032:analysis; D010743:Phospholipids / Q000032:analysis
chemical_list: D015415:Biomarkers; D010743:Phospholipids; C075750:8-epi-prostaglandin F2alpha; D009569:Nitric Oxide; D007633:Keratins; D015237:Dinoprost; D006861:Hydrogen Peroxide