Results

Higher than normal levels of exhaled nitric oxide generally mean your airways are inflamed — a sign of asthma.

An oral exhaled nitric oxide value more than 40 parts per billion for adults and more than 25 parts per billion for children and adolescents is considered elevated.

Nitric oxide test results can vary widely from person to person. When interpreting test results, your doctor will consider a number of other factors. These may include:

• Your asthma signs and symptoms
• Past nitric oxide test results
• Results of other tests, such as peak flow tests or spirometry tests
• Medications you take
• Whether you have a cold or the flu
• Whether you have hay fever or other allergies
• Whether or not you smoke
• Your age