A nitric oxide test, or more correctly an exhaled nitric oxide test, is one of the many tests through which asthma can be diagnosed. In addition, this test can measure the effectiveness of asthma medications. Since it has been developed recently, it is administered in only certain doctor’s offices and hospitals.

In an exhaled nitric test, the patient breathes (exhales) into a mouthpiece (breath tube). The mouthpiece is connected to a device, which measures the amount of nitric oxide in the breath.

Asthma is a disease characterized by the inflammation of the bronchial tubes, or airways, of the lungs. These inflamed bronchial tubes release nitric oxide. Therefore, a high level of nitric oxide in the breath indicates a high extent of inflammation of the airways, even though several other natural processes in the body also release nitric oxide.

The exhaled nitric test has become popular lately due to the relative simplicity through which it can be carried out; the test lasts for just 10 seconds and the results can be accesses within 60 seconds. However, if administered alone, the test is not a reliable tool for diagnosing asthma. That’s why it must be accompanied by lung function tests, such as spirometry and peak flow measurement, for diagnosing asthma correctly.