Exhaled Breath Condensate as a Non-Invasive Biomarker of Oxidative Stress in Smokers: A Cross-Sectional Case–Control Study
Oxidative Stress
DOI:
https://doi.org/10.63939/vfzgj933Keywords:
Exhaled breath condensate, oxidative stress, hydrogen peroxide, 8-isoprostane, smokers, biomarkers, total antioxidant capacity, , non-invasive diagnosticsAbstract
Introduction: smoking remains a major global health burden, driving disease through persistent oxidative stress and impaired antioxidant defenses. Traditional serum assays provide valuable information but are invasive and impractical for large-scale screening. Exhaled breath condensate (EBC) offers a simple, non-invasive alternative for assessing oxidative biomarkers in the airways.
Objectives: This study aimed to evaluate whether oxidative stress biomarkers measured in EBC reflect systemic oxidative changes in apparently healthy smokers and to determine their diagnostic performance.
Methods: A cross-sectional, case–control study was conducted among 60 adults (30 smokers, 30 non-smokers) aged 18–45 years. EBC was collected using a standardized condenser system, and both EBC and serum samples were analyzed for hydrogen peroxide (H₂O₂), 8-isoprostane, malondialdehyde (MDA), and total antioxidant capacity (TAC). Data were analyzed using t-tests, correlation analyses, and receiver-operating-characteristic (ROC) curves.
Results: Smokers showed markedly higher oxidative-stress biomarkers in both EBC and serum compared with non-smokers. Mean EBC H₂O₂ was 1.84 ± 0.42 µM in smokers versus 0.96 ± 0.28 µM in controls (p < 0.001), and EBC 8-isoprostane levels were 57.4 ± 14.3 pg/mL versus 33.1 ± 10.8 pg/mL (p < 0.001). TAC values were significantly lower in smokers across both matrices. EBC H₂O₂ correlated strongly with serum MDA (r = 0.61, p < 0.01), indicating concordant airway and systemic oxidative stress. ROC analysis showed high diagnostic accuracy for EBC H₂O₂ (AUC = 0.87, 95% CI 0.77–0.95).
Conclusions: EBC biomarkers, particularly H₂O₂ and 8-isoprostane, reliably mirror systemic oxidative stress in cigarette smokers. The strong correlation between EBC and serum markers supports EBC as a non-invasive, reproducible, and clinically relevant tool for early detection of smoking-related oxidative injury. Its simplicity and low cost make it especially promising for preventive health programs and research in low- and middle-income settings
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