Exhaled breath condensate pH and hydrogen peroxide as non-invasive markers for asthma.

Objective: To estimate the predictive value of exhaled breath condensate (EBC) hydrogen peroxide (H2O2) concentration and pH as non-invasive markers in asthma.
Methods: Fifty patients with unstable, steroid naive atopic asthma were included in the study, 25 with intermittent asthma and 25 with persistent asthma. Asthma diagnosis was according to the National Heart Lung and Blood Institute guidelines for the diagnosis and management of asthma. Forced expiratory volume in one second (FEV1) was measured by computerized spirometry. The EBC H2O2 assay was carried out using the colorimetric assay. The study was conducted from January to December 2005 in the Asthma and Allergy Center, Tikrit, Iraq.
Results: The EBC H2O2 concentration was higher in the asthmatic group (0.91 micromol) as compared with the control (0.23 micromol). There was an inverse correlation between EBC H2O2 concentration and FEV1 predicted percent for asthmatic patients. The mean EBC pH was lower in the asthmatic than the control group. There was a positive correlation between EBC pH and FEV1 predicted percent for asthmatic patients. There was an inverse correlation between EBC H2O2 concentration and pH for all asthmatic patients, intermittent, and persistent asthmatic groups.
Conclusion: Exhaled breath condensate hydrogen peroxide concentration and pH was a good non-invasive marker for asthma, whether it was with a persistent or intermittent course.