Exhaled nitric oxide as a marker of lung involvement in Crohns disease.

Crohn’s Disease (CD) is an inflammatory bowel disease that is often associated with a variety of systemic manifestations, including airways involvement. The latter is in most cases subclinical, and requires expensive and invasive methods to be diagnosed. Fractional Exhaled Nitric Oxide (FENO) can be measured non invasively at low (bronchial air) and high (alveolar air) flows to reflect proximal airway inflammation, and systemic inflammation. The aim of our study was to compare both bronchial and alveolar FENO as an index of pulmonary involvement and of systemic inflammation in CD patients with at different stages of clinical activity and different treatments, with a group of healthy subjects studied. Thirty CD patients (age 43.10 ± 14.6 yrs) without clinical evidence of pulmonary diseases and 21 non smokers, not atopic healthy controls (age 35.1 ± 13.2 yrs) were enrolled. FENO was measured using a chemiluminescence analyzer at high and low flows. Bronchial (14.9 ± 10.2 ppb vs 10.1 ± 6.3 ppb, p=0.049) and alveolar FENO (4.4 ± 2.2 ppb vs 2.6 ± 1.9; p=0.006) were significantly higher in Crohn’s disease than in healthy controls, respectively, and bronchial FENO was significantly higher in CD patients treated with immunomodulators (20.4 + 11.5 ppb) than in those treated with mesalazine (7.9 + 4.2 ppb, p=0.04). Both bronchial (p=0.0016) and alveolar FENO (p=0.017) were positively correlated with Crohn’s Disease Activity Index. In conclusion, our results for bronchial FENO confirm subclinical pulmonary involvement in Crohn’s disease. Alveolar FENO may be of clinical value during follow-up of these patients as a surrogate marker of systemic inflammation