Hydrogen peroxide in breath condensate during a common cold
Background: Hydrogen peroxide (H2O2) in exhaled air condensate is elevated in inflammatory disorders of the lower respiratory tract. It is unknown whether viral colds contribute to exhaled H2O2. Aim: To assess exhaled H2O2during and after a common cold. Methods: We examined H2O2in the breath condensate of 20 normal subjects with acute symptoms of a common cold and after recovery 2 weeks later and, similarly, in 10 subjects without infection. H2O2was measured with a fluorimetric assay. Results: At the time of infection exhaled H2O2(median, ranges) was 0.20 μM (0.03-1.2 μM), and this decreased to 0.09 μM (< 0.01-0.40 μM) after recovery (p = 0.006). There was no significant difference in lung function (forced vital capacity and forced expiratory volume in 1 sec) during and after colds. In the controls, exhaled H2O2did not change over a 2-week period. Conclusions: H2O2in exhaled air condensate is elevated during a common cold, and returns to normal within 2 weeks of recovery in healthy subjects. Hence, symptomatic upper respiratory tract infection may act as a confounder in studies of H2O2as a marker of chronic lower airway inflammation.