Exhaled Nitric Oxide - Other Conditions

Other Conditions

The role for eNO in other conditions is even less well established compared to asthma.

Since asthma can be a cause of chronic coughing (it may even be the sole manifestation, such as in cough-variant asthma), studies have looked at whether eNO can be used in the diagnosis of chronic cough.

Exhaled NO is minimally increased in chronic obstructive pulmonary disease, but levels may rise in sudden worsenings of the disease (acute exacerbations) or disease progression. Early findings indicate a possible role for eNO in predicting the response to inhaled glucocorticoids and the degree of airway obstruction reversibility.

Children with cystic fibrosis have been found to have low eNO levels. In subjects with bronchiectasis (a state of localized, irreversible dilatation of part of the bronchial tree) not due to cystic fibrosis, high levels have been found. Sarcoidosis could also feature increased eNO. Low levels have been found in primary ciliary dyskinesia, bronchopulmonary dysplasia, and pulmonary arterial hypertension. In the latter condition, inhaled NO is used as a diagnostic test of the response of the pulmonary arteries to vasodilators (agents that relax the blood vessels).

Exposure to air pollution has been associated with decreased, and increased eNO levels.