Tests to Diagnose Asthma

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If you have chest tightness, a persistent cough, shortness of breath, or notice a whistling sound when you breathe, you may have asthma. Asthma is a chronic (long-term) lung disease that is marked by inflammation and narrowing of the airways. However, just because you have these typical asthma symptoms doesn't mean you have asthma. Other conditions have similar symptoms, including emphysema and acute bronchitis. Sometimes these asthma-like symptoms occur briefly without a serious underlying disease. The only way to find out if asthma or another disease is causing your symptoms is to see your doctor.

An Asthma Diagnosis Begins With a Thorough Evaluation

In order to determine the cause of your symptoms, your doctor will perform a complete medical evaluation. Your doctor will ask you questions about the type of symptoms you have, how severe they are, and when they occur. Before you go to the doctor, ask yourself if certain activities or substances seem to trigger your symptoms. Common asthma triggers include vigorous exercise, cold air, smoke, pollen, and animals with fur or feathers.

Your doctor will also ask about your overall health and family medical history, including a history of allergies and allergy-related skin conditions, such as eczema. Many people with allergies also have asthma. You doctor will also perform a physical exam and listen to your lungs with a stethoscope to check for wheezing—a whistling sound that is made when you breathe—and decreased breathing sounds as you take deep breaths.

What Tests Are Used to Diagnose Asthma?

Your doctor will run some tests to confirm if you have asthma and to eliminate other possible diagnoses. Tests for asthma can help determine the type and severity of your asthma. The test results can also help your doctor choose the most appropriate and effective treatment plan for you. There are tests that measure pulmonary, or lung function; allergy tests; and imaging tests:

  • Lung function test measures how much air you can move in and out of your lungs. The test is easy and painless. You breathe into a machine as it takes measurements, such as how much air your lungs hold. It can also show if your lungs are damaged.

  • Bronchoprovocation test is a lung function test that measures your lung function after you are exposed to factors that commonly trigger asthma, such as exercise and cold air.

  • Methacholine challenge test is a specific lung function test in which you inhale a drug called methacholine (Provocholine). This drug constricts the airways in certain people. If your airways constrict, then you will take an airway-opening drug. If this drug opens your airways, you probably have asthma.

  • Allergy tests, such as a skin patch test and blood test, can determine if you are sensitive to certain allergens. Allergens are substances that cause an allergic reaction that can lead to asthma symptoms. In a skin patch test, small amounts of common allergens are applied to your skin to determine which ones trigger your allergic response. A radioallergosorbent test (RAST) is another type of allergy test to identify certain allergens in your blood.

  • Chest X-ray can check for other diseases and conditions with respiratory symptoms that are similar to asthma. These include pneumonia, heart failure, and bronchitis.

Your doctor can tell you for sure if you have asthma. If you do have asthma, there is a variety of effective treatments available to help prevent and control your asthma symptoms. Your doctor will create an asthma action plan designed especially for you. If you follow your asthma action plan avoid your asthma triggers, you can keep your asthma in check and feel your best.

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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2020 Feb 11

  1. Asthma. American Academy of Allergy Asthma & Immunology. http://www.aaaai.org/conditions-and-treatments/asthma.aspx

  2. How does a doctor test for asthma? Hands on Health South Carolina. http://www.handsonhealth-sc.org/page.php?id=931

  3. How Is Asthma Diagnosed? National Institutes of Health. National Heart, Lung, and Blood Institute. http://www.nhlbi.nih.gov/health/health-topics/topics/asthma/diagnosis

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