ABSTRACT
<p><b>OBJECTIVE</b>To explore the relationship between nitrite levels in the exhaled breath condensates (EBC) and the severity of asthma.</p><p><b>METHODS</b>Sixty asthmatic patients with exacerbation (including 23 with mild, 21 with moderate, and 16 with severe asthma) and 23 healthy nonsmokers were enrolled in this study. The lung function tests were performed and nitrite levels measured in the EBC by the spectrophotometry and nitric oxide assay kit in these subjects. The percentage of eosinophils was also measured in induced sputum by Wright staining.</p><p><b>RESULTS</b>The concentrations of nitrites in the EBC and the percentage of eosinophils in induced sputum in the asthmatic patients were significantly higher than those of the healthy subjects (P<0.01), and showed positive correlations to the disease severity. A significant positive correlation was found between nitrites in the EBC and percentage of eosinophils in induced sputum (r=0.706, P<0.01). The concentration of exhaled nitrites was inversely correlated to MEF50% (r=-0.806, P<0.01) and FEV1% (r=-0.724, P<0.01).</p><p><b>CONCLUSION</b>Nitrite level in the EBC may serve as useful indicators for estimating the severity of asthma.</p>