Lung Function Tests
Reviewed
Also called: Pulmonary function tests, PFTs
Lung function tests check how well your lungs are working. They measure how much air your lungs can hold, how well you move air in and out, and how well your lungs absorb oxygen into your blood. These tests help diagnose and monitor lung diseases, guide treatment decisions, check lung function before surgery, and check for lung damage from exposure to substances.
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
Wear loose, comfortable clothing. Do not eat a large meal within at least two hours of the test. You may need to avoid heavy exercise, smoking, alcohol, caffeine, and certain inhaler medicines before the test. Follow your provider's instructions. Never stop taking any medicine without talking with your provider first.
not applicable
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.
Understanding results
Your provider will compare your results to those of healthy people of the same height, age, and sex. If results are not normal, they may indicate an obstructive or restrictive lung condition. Further evaluation is needed to determine the specific cause.
- Normal: Your results are within the expected range for a person of your height, age, and sex. Limitation: A normal result does not rule out all lung conditions. Your provider will interpret results in the context of your overall health. Next step: No specific follow-up is needed based on this test alone. Discuss any ongoing symptoms with your provider.
- Obstructive pattern: Your airways are narrow, making it hard for air to flow out of your lungs. Limitation: This pattern cannot diagnose a specific disease. Examples of obstructive lung diseases include asthma, bronchitis, and emphysema. Next step: Your provider may order additional tests to identify the specific obstructive lung disease.
- Restrictive pattern: Your lungs cannot hold as much air as normal, often because your lungs or chest muscles cannot expand fully. Limitation: This pattern cannot diagnose a specific disease. Examples of restrictive lung conditions include scleroderma, sarcoidosis, pulmonary fibrosis, and interstitial lung diseases. Next step: Your provider may order additional tests to identify the specific restrictive lung condition.
- 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
Your provider will compare your results to those of healthy people of the same height, age, and sex. If results are not normal, they may indicate an obstructive or restrictive lung condition. Further evaluation is needed to determine the specific cause.
- 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?