Tests and diagnosis

By Mayo Clinic Staff

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Your doctor will probably start by doing a physical exam that includes your ears, nose, throat and chest and may ask you a number of questions.

You may need one or more tests to see what's going on and to make sure your symptoms aren't caused by something other than exercise-induced asthma. If you do have asthma, your doctor may want to do tests to determine how well your lungs are working and if something other than exercise also triggers your symptoms.

However, extensive testing isn't always needed to diagnose exercise-induced asthma. Your doctor may give you an inhaler to try before exercise. If it works, you probably do have asthma. For many people with exercise-induced asthma, taking one or two puffs of albuterol or another inhaled medication before exercise is enough to ease symptoms.

Ruling out other conditions

If it isn't clear whether asthma's causing your symptoms, your doctor may do tests to see whether your symptoms may be caused by something else. Other health problems that can mimic exercise-induced asthma include:

  • Being out of shape
  • Heart disease or heart failure
  • Lung disorders
  • Central airway obstruction
  • Vocal cord problems
  • Hay fever or other allergies

Lung function tests

To see how well your lungs are working, and to see whether you show signs of asthma, you may need lung function tests that may include:

  • Lung function test (spirometry). This test, which measures how well you breathe, is the preferred test for diagnosing asthma. During this 10- to 15-minute test, you take deep breaths and forcefully exhale into a tube connected to a machine called a spirometer. If certain key measurements are below normal for a person your age and sex, your airways may be blocked by inflammation (obstructed). This is a key sign of asthma. Your doctor may ask you to inhale a bronchodilator drug used in asthma treatment to open your airways. Then you retake the spirometry test. If your breathing improves significantly, it's likely you have asthma.
  • Exercise challenge. Because spirometry that's done while you're at rest won't always pick up exercise-induced asthma, this test is used to see how exercise affects your lung function. With this test, your doctor may have you do a lung function test before and after you exercise. Exercise is usually done for six to eight minutes on a treadmill or other stationary workout machine. For competitive athletes, exercise challenge tests are sometimes done in the sporting environment.
  • Peak flow measurement. To determine if you have asthma, and how well your lungs work, your doctor may ask you to carry a peak flow meter. This small, hand-held device measures how fast you can force air out of your lungs. The slower you exhale, the worse your asthma. You'll likely be asked to use your peak flow meter at certain times, such as during or following exercise.
  • Methacholine (Provocholine) challenge. During a methacholine (meth-uh-KOH-leen) challenge test, you inhale a small amount of methacholine mist to see if it causes asthma symptoms. Your lung function is tested before and after the methacholine is given to see how much it affects your ability to breathe. Challenge testing may also be done using cold air, mannitol or histamine. These tests are done only at specialized clinics.
  • Allergy skin tests. During a skin test, your skin is pricked with purified allergy extracts and observed for signs of an allergic reaction. These tests may be useful to see whether you have a reaction to things other than exercise, such as animal dander, mold, dust mites or latex.
Nov. 08, 2011