Exhaled nitric oxide as a marker of atopic asthma

The aim of the present study was to assess the effect of atopy and regular therapy for asthma on exhaled nitric oxide (eNO). Exhaled NO was measured using a chemi-luminescence analyzer during slow expiration in 83 children, aged 5-7 years, after hospitalization for wheezing in infancy. The mean (± SD) age of the subjects was 7.2 ± 0.7 years, 28% were girls and 42% were atopic. A total of 31 children (37%) had asthma with regular medication: 20 were taking cromones, and 11 were taking inhaled steroids. In the asthma group, the median concentration of eNO was 14.9 p.p.b. (range 3.5-56.1 p.p.b.) in atopics and 7.3 p.p.b. (range 5.1-15.6 p.p.b.) in non-atopics (P < 0.01). The levels for atopic children on cromones tended to be higher than for those on inhaled steroids; however, the difference did not reach statistical significance. We conclude that eNO concentrations associate significantly with atopic asthma.