Exhaled and nasal nitric oxide in relation to lung function, blood cell counts and disease characteristics in cystic fibrosis

Abstract

Background. Patients with cystic fibrosis (CF) have similar or lower exhaled nitric oxide (FeNO) and lower nasal nitric oxide (nNO) levels than controls. There are divergent results on alveolar NO (CalvNO) concentrations in relation to CF. There are inconsistent results on correlation between different nitric oxide parameters and lung function and inflammation in CF. Aim. To compare FeNO, CalvNO and nNO levels between subjects with CF, asthma and healthy controls and to study whether these parameters are related to lung function, blood cell counts or clinical characteristics in CF patients. Material and methods. Measurements of FeNO at multiple exhalation flow rates, nNO and spirometry were done in 38 patients (18 adults) with CF. Blood cell counts and CF clinical characteristics were recorded. Thirty-eight healthy controls and 38 asthma patients, gender- and age-matched, were included as reference groups. Results. FeNO levels were lower in CF patients (7.2 [4.7–11.2] ppb) than in healthy controls (11.4 [8.3–14.6] ppb) and asthma patients (14.7 [8.7–24.7] ppb) (both p < 0.005). These differences were consistent in adults. No difference in CalvNO was seen between the groups. nNO levels in CF patients (319 [193–447] ppb) were lower than in healthy controls (797 [664–984] ppb) and asthma patients (780 [619–961] ppb) (both p < 0.001). FeNO positively related to FEV1 (rho = 0.51, p = 0.001) in CF patients and this was consistent in both adults and children. A negative correlation was found between FeNO and blood neutrophil counts (rho = −0.37, p = 0.03) in CF patients. Conclusion. CF patients have lower FeNO and nNO and similar CalvNO levels as healthy controls and asthma patients. Lower FeNO related to lower lung function in both adults and children with CF. Furthermore, in CF, lower FeNO also related to higher blood neutrophil counts.