A diagnosis of
asthma is based on your
medical history, a
physical exam, and lung function tests.
Lung function tests
Lung function tests can diagnose asthma, show how
severe it is, and check for complications.
- Spirometry is the most common test to diagnose asthma. It measures how quickly you can move air in and out of the
lungs and how much is moved.
- Testing of daytime changes in
peak expiratory flow (PEF) is done over 1 to 2 weeks.
This test is needed when you have symptoms off and on but have normal
spirometry test results.
exercise or inhalation challenge may be used if the
spirometry test results have been normal or near normal but asthma is still
suspected. These tests measure how quickly you can breathe in and out after
exercise or after using a medicine. An inhalation challenge also may be done
using a specific irritant or
allergen if your doctor suspects occupational asthma.
Tests for other diseases
Asthma can be hard
to diagnose because the symptoms vary widely. And asthma-like symptoms can also be caused by other conditions, such
as a viral lung infection or a
vocal cord problem. So your doctor may want to do one or more extra tests.
- More lung function tests may be needed
if your doctor suspects another lung disease, such as
electrocardiogram (EKG, ECG) might be done to
rule out serious conditions with similar symptoms, such as
chronic heart failure. This test measures the electrical
signals that control the rhythm of your heartbeat.
bronchoscopy test can be done to examine the airways for problems such as
tumors or foreign bodies. This test uses a long, thin, lighted tube to look at your airways.
- Biopsies of the airways can be done to look for
changes that point to asthma.
chest X-ray may be used to look for signs of other lung
diseases, such as fibrous tissue caused by chronic inflammation (pulmonary
- Blood tests, such as a
complete blood count (CBC), may be done to look for
signs of an infection or other condition.
You need to
monitor your condition and have regular checkups to
keep asthma under control and to review and possibly update your
asthma action plan. Checkups are recommended every 1
to 6 months, depending on how well your asthma is controlled.
During checkups, your doctor will ask about information you may have tracked in an
asthma diary, such as:
- Whether your symptoms and
peak expiratory flow have held steady, improved, or
become worse. You may be asked to bring your
peak expiratory flow meter to an appointment so your
doctor can see how you use it.
- Asthma attacks during exercise or at night.
Based on the results, your asthma category may
change, and your doctor may change the medicines you use or how much medicine
Tests to identify triggers
If you have persistent
asthma and take medicine every day, your doctor may ask about your exposure to
substances (allergens) that cause an allergic reaction. For more
information about testing for triggers, see the topic
Allergy tests can include skin tests and a blood test. Skin tests are needed if you are interested in allergy