Oxidative stress levels in exhaled breath condensate associated with COPD and smoking.

BACKGROUND COPD is characterized by chronic air-flow limitation. Smoking is the most important factor in the pathogenesis of COPD. Smoking is associated with increased oxidative stress in the lungs. In this study our aim was to evaluate the differences in the burden of oxidative stress in patients with COPD, smokers, and non-smokers by measuring hydrogen peroxide (H(2)O(2)), malondialdehyde (MDA), and 8-isoprostane levels in the exhaled breath condensate (EBC) samples. METHODS Eighty subjects were included in the study. Group I (no. = 25) had COPD, Group II (no. = 26) was smokers, and Group III (no. = 29) was nonsmokers. The severity of the COPD and dyspnea was assessed according to the results of pulmonary function tests (PFTs) and Medical Research Council (MRC) scale. RESULTS The mean age of the subjects was 58 ± 8.9 years. While 8-isoprostane and H(2)O(2) levels were significantly higher in subjects with COPD (44.8 ± 40.2 pg/mL and 1.9 ± 0.8 μmol/L) and smokers (41.3 ± 26 pg/mL and 1.7 ± 0.7 μmol/L) than non-smokers (15.8 ± 6.9 pg/mL and 0.8 ± 0.4 μmol/L), levels were similar between smokers and COPD subjects. MDA levels were similar between the 3 groups (P = .31). There was no correlation between 8-isoprostane and H(2)O(2) levels and PFT parameters. There was a significant positive correlation between dyspnea grade on the MRC scale and 8-isoprostane levels (r = 0.805, P < .001). CONCLUSIONS Even if respiratory function tests are within normal limits, oxidant burden in lungs of smokers is equivalent to that in COPD patients. 8-isoprostane could be useful in assessing symptom severity and health status of COPD patients.