Skip to content
My WebMD Sign In, Sign Up

Asthma Health Center

Font Size

Asthma and Lung Function Tests

Lung function tests are a way to check how well your lungs are working. Doctors use lung function tests to diagnose asthma and to monitor its progression. Monitoring asthma with lung function tests is helpful because you may not always be able to tell -- just from your symptoms -- whether or not your asthma is under control.

In most cases, you have lung function tests in an exam room that contains special devices to measure lung function. A specially trained respiratory therapist or technician is likely to do the tests.

Recommended Related to Asthma

Allergy Tests and Asthma

Allergy tests are a way to get to the bottom of what's causing your asthma symptoms. They help your doctor find your asthma triggers and prevent breathing problems. But allergy tests alone are not enough to make an asthma diagnosis. Your doctor will look at your history of allergic reactions, too. Several types of allergy tests help with asthma, including skin tests and blood tests. The results of your allergy tests may show what's triggering your asthma and allergy symptoms, and that can help...

Read the Allergy Tests and Asthma article > >

Ask your doctor if you should do anything to prepare for your lung function tests. For instance, you might need to adjust your medication. You may also need to avoid heavy meals, smoking, and any irritants or other substances that might trigger an asthma attack.

Types of Lung Function Tests

These lung function tests are commonly used to diagnose and monitor asthma:

  • Spirometry is the most common of the lung function tests used for asthma. It's a simple, quick, and painless way to check your lungs and airways. You just take a deep breath and exhale into a hose attached to a device called a spirometer. It records how much air you blow out (FVC, or forced vital capacity) and how quickly you do it (FEV, or forced expiratory volume). Your score is lower if your airways are swollen or constricted because of asthma or other lung diseases. Your doctor may want you to have several spirometry lung function tests to monitor your asthma over time. You might have spirometry before and after you take medication to see if the medication helps. Your doctor may also want readings taken during exercise to see how your airways react to exercise.
  • Challenge tests are lung function tests used to help confirm a diagnosis of asthma. You inhale a small amount of a substance known to trigger symptoms in people with asthma, such as histamine or methacholine. After inhaling the substance, someone tests your lung function. Because challenge tests can trigger an asthma attack, you should only have them done by someone with experience.
  • Peak flow meter tests measure how well your lungs push out air. Although they are less accurate than spirometry, these lung function tests can be a good way to regularly test your lung function at home -- even before you feel any symptoms. A peak flow meter can help you know what makes your asthma worse, whether treatment is working, and when you need to seek emergency care.

A peak flow meter is a handheld plastic tube with a mouthpiece on one end, which you breathe into. Your doctor might ask you to use the peak flow meter each day and write down the readings. After a couple of weeks, you report the results to your doctor.

 

WebMD Medical Reference

When Is Your Asthma Worse?

When Is Your Asthma Worse?

Take the WebMD Asthma assessment to get Personalized Action Plan

Start Now

Today on WebMD

Distressed woman
Slideshow
Woman holding an asthma inhaler
Article
 
Get Personalized Asthma Advice
Health Check
asthma overview
Slideshow
 
Los Angeles skyline in smog
Slideshow
man in a field with allergies
Slideshow
 
Woman holding inhaler
VIDEO
Slideshow Allergy Myths and Facts
Slideshow
 

Pollen counts, treatment tips, and more.

It's nothing to sneeze at.

Loading ...

Sending your email...

This feature is temporarily unavailable. Please try again later.

Thanks!

Now check your email account on your mobile phone to download your new app.

Man outdoors coughing
Article
Lung and bronchial tube graphic
Article
 
10 Worst Asthma Cities
Slideshow
runner
Article