An increase in exhaled nitric oxide is not associated with activity in pulmonary sarcoidosis

Exhaled nitric oxide (eNO) concentration measurement may permit the noninvasive estimation of the severity of airways inflammation in respiratory tract diseases. The aim of this study was to evaluate the correlation between eNO concentration and the activity of sarcoidosis, its radiographic staging and lung function abnormalities. eNO concentration was measured using a chemiluminescent analyser in 27 patients with sarcoidosis and 11 control subjects. The mean eNO concentration in patients with sarcoidosis was significantly higher (6.7+/-0.50 parts per billion (ppb)) than that in the control group (5.17+/-0.73 ppb). eNO concentration was similar in radiographic stage I, II and III patients (6.53, 7.32 and 6.24 ppb, respectively). No significant difference was found in eNO concentration between the patients with active and inactive disease. Nor did eNO concentration differ between the patients with and without indication for therapy. There was no significant correlation between eNO concentration and forced vital capacity or bronchoalveolar lavage fluid lymphocyte and macrophage counts. There was a weak correlation between eNO concentration and single-breath carbon monoxide diffusing capacity of the lung. Exhaled nitric oxide concentration is elevated in patients with sarcoidosis. This concentration does not depend on the radiographic staging, activity or progression of the disease.