Lung Function Tests
Reviewed
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.
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.
Understanding this test
Use the reference interval and units printed by the laboratory that performed the test. A result outside that interval is not a diagnosis by itself, and a result inside it does not rule out every condition. Your symptoms, history, medicines, timing, and related tests can change what the result means.
- 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.