Tests are only part of making an asthma diagnosis. Your healthcare provider will not only ask about your asthma symptoms (wheezing, chest tightness, shortness of breath, and cough) but also about your family history, personal history and perform a physical exam. Symptoms such as decreased exercise capacity or a night time cough are common among asthmatics. Likewise, symptoms are more likely to be asthma if they occur after exposure to furry pets, after exposure to high pollen levels, or exposure to dust and molds. A personal history of atopic dermatitis, hay fever, and allergic rhinitis all increase your risk of asthma. Similarly, having a parent, brother or sister with asthma increases one’s risk of developing asthma.
It is important for you to learn how to use your peak-flow-meter appropriately.
Peak flow is used to monitor rather than diagnose asthma. Normals are based on your age and height. It is important to determine your personal best peak flow so that you can base treatment changes off your asthma action plan.
Lung Volumes: Your asthma care provider may order body plethysmography test to determine your lung volumes. Asthma may cause certain changes in lung volumes that will assist your asthma care provider in diagnosing or treating your asthma. Diffusion Capacity: Diffusion capacity measures how well oxygen flows from the lungs into your blood. Poor diffusion indicates damage to the lung where the oxygen and blood meet in the lungs. Diffusion capacity is usually normal in asthmatics.
The test is simple and noninvasive: It involves exhaling slowing and steadily (rather than forcefully, as is the case of other lung function tests) into a handheld instrument. The device measures the amount of nitric oxide in the breath in parts per billion (PPB). FeNO takes place in a healthcare provider’s office and the results of the test are available immediately.
FeNo testing was one focus of a National Institutes of Health panel of experts who issued updated guidelines for asthma management in December 2020. According to their recommendations, FeNO testing should not be used alone to diagnose or monitor asthma, but can be helpful as an add-on test when a person’s symptoms and spirometry and other tests aren’t conclusive.
The guidelines apply only to adults and children 5 and over. The panel advised against FeNO testing for younger children as a way to assess wheezing, as studies show it to be an unreliable way to predict if they ultimately will develop asthma.
