Lung Function Tests
Reviewed
Also called: Pulmonary function tests, PFTs
Lung function tests are a group of tests that check how well your lungs are working. These tests are also called pulmonary function tests, or PFTs.
Specimen: not applicable
Why this test may be ordered
- To help diagnose and monitor lung diseases such as asthma, COPD, emphysema, pulmonary fibrosis, and pulmonary hypertension.
- To guide decisions about treating certain lung diseases with medicine.
- To help diagnose and monitor diseases that can affect the lungs, such as scleroderma or sarcoidosis.
- To check lung function before surgery.
- To check for lung damage from exposure to chemicals or other substances at home or work.
Preparation and collection
Your provider will let you know how to prepare for your lung function test. Don't eat a large meal within at least two hours of the test. If you use inhaler medicines (bronchodilators), you may need to stop for a period of time before testing. Your provider will tell you when to stop. But never stop taking any medicine without talking with your provider first.
There are different ways to do each type of lung function test. But the basic steps are about the same. For a spirometry test: You'll sit on a chair with a soft clip on your nose. The spirometer will measure how much air you breathe out and how fast you blow it out.
There is very little risk to having a lung function test. Some people may feel lightheaded, dizzy, or tired from breathing hard. Some people may feel nervous being in a small space for a lung volume test. If you have concerns about your test, talk with your provider.
Understanding results
A normal lung function test result for you depends on the size of your lungs. So, your provider will compare your test results to results from healthy people who are the same height, age, and sex as you.
- Obstructive pattern: Obstructive lung conditions cause your airways to become narrow, making it hard for air to flow out of your lungs. Examples of obstructive lung diseases include asthma, bronchitis, and emphysema. Limitation: Lung function tests can't diagnose which specific lung disease you have. Next step: If you have questions about your results, talk with your provider.
- Restrictive pattern: Restrictive lung conditions decrease the amount of air your lungs can hold. Examples of restrictive lung conditions include scleroderma, sarcoidosis, pulmonary fibrosis, and interstitial lung diseases. Limitation: Lung function tests can't diagnose which specific lung disease you have. Next step: If you have questions about your results, talk with your provider.
- There is very little risk. Some people may feel lightheaded, dizzy, or tired from breathing hard. Coughing is common. Some may feel nervous in a small space for a lung volume test.
- The test cannot diagnose a specific lung disease; it indicates whether the pattern is obstructive or restrictive.
What to do next
If you have questions about your results, talk with your provider. If you need one or more lung function tests, your provider may also order a blood oxygen level test called an arterial blood gas (ABG) test.
- Do you have signs or symptoms of a breathing problem, such as shortness of breath, wheezing, coughing, or a tight feeling in your chest?
- Do you have a lung condition or another condition that could damage your lungs?
- Have you been exposed to substances that can cause lung damage, such as asbestos, radiation, or certain medicines?
- Are you going to have surgery?
Evidence source
Source: U.S. National Library of Medicine (MedlinePlus). Practices and reference ranges may differ in your country.