How is Adult-Onset Asthma Diagnosed?
Your asthma doctor may diagnose adult-onset asthma by:
- Taking a medical history, asking about symptoms, and listening to you breathe
- Performing a lung function test, using a device called a spirometer, to measure how much air you can exhale after first taking a deep breath and how fast you can empty your lungs. You may be asked before or after the test to inhale a short-acting bronchodilator (medicine that opens the airways by relaxing tight muscles and that also help clear mucus from the lungs).
- Performing a methacholine challenge test; this asthma test may be performed if your symptoms and spirometry test do not clearly show asthma. When inhaled, methacholine causes the airways to spasm and narrow if asthma is present. During this test, you inhale increasing amounts of methacholine aerosol mist before and after spirometry. The methacholine test is considered positive, meaning asthma is present, if the lung function drops by at least 20%. A bronchodilator is always given at the end of the test to reverse the effects of the methacholine.
- Performing a chest X-ray. An X-ray is an image of the body that is created by using low doses of radiation reflected on special film or a fluorescent screen. X-rays can be used to diagnose a wide range of conditions, from bronchitis to a broken bone. Your doctor might perform an X-ray exam on you in order to see the structures inside your chest, including the heart, lungs, and bones. By viewing your lungs, your doctor can see if you have a condition other than asthma that may account for your symptoms. Although there may be signs on an X-ray that suggest asthma, a person with asthma will often have a normal chest X-ray.
Who Gets Asthma?
Anyone can get asthma at any age. Among those at higher risk for asthma are people who:
- Have a family history of asthma
- Have a history of allergies (allergic asthma)
- Have smokers living in the household
- Live in urban areas
How is Asthma Classified?
Asthma is classified into four categories based upon frequency of symptoms and objective measures, such as peak flow measurements and/or spirometry results. These categories are: mild intermittent; mild persistent; moderate persistent; and severe persistent. Your physician will determine the severity and control of your asthma based on how frequently you have symptoms and on lung function tests. It is important to note that a person's asthma symptoms can change from one category to another.