Pulmonary Function Tests: Understanding How Well Your Lungs Work

Angela Nguyen
24 minutes ago
3 min read

What Are Pulmonary Function Tests?

Pulmonary Function Tests (PFTs) are a set of breathing tests used to evaluate how well your lungs take in air, move it out, and diffuse oxygen throughout the body. They help healthcare providers understand lung performance and identify conditions that may affect breathing. These tests are often used in both routine checkups and specialty clinics.

What PFTs Measure

Rather than focusing on one single number, PFTs provide an extensive picture of lung function by measuring:

Lung volumes: how much air the lungs can hold
Airflow: how quickly air can be inhaled or exhaled
Gas exchange: how efficiently oxygen moves into the blood

Together, these measurements help distinguish between different types of lung problems, such as obstructive or restrictive patterns.

Common Types of PFTs

Several tests may be included in a PFT session, including:

Spirometry: measures how much and how fast you can breathe out
Lung volume tests: assess total lung capacity
Diffusion capacity (DLCO): evaluates how well oxygen passes from the lungs into the bloodstream

A provider may use one or multiple tests to get a complete assessment.

What to Expect During the Test

PFTs are usually performed in a clinic or hospital setting. You’ll be asked to breathe through a mouthpiece while following specific instructions, such as taking a deep breath or exhaling forcefully. Nose clips are often used to ensure accuracy.

The test is non-invasive and generally safe, though some people may feel lightheaded or short of breath briefly. In some cases, the test may be repeated after using a bronchodilator to see how the lungs respond to medication.

How Results Are Interpreted

PFT results are compared to predicted values based on age, sex, height, and ethnicity. Patterns in the results help providers determine whether lung function is:

Normal
Obstructive (such as asthma or chronic obstructive pulmonary disease)
Restrictive (such as pulmonary fibrosis or chest wall conditions)

Results are interpreted alongside symptoms, medical history, and other tests, not on their own.

When Pulmonary Function Tests Are Used

PFTs may be ordered to:

Evaluate unexplained shortness of breath
Diagnose or monitor chronic lung diseases
Assess response to respiratory treatments
Screen lung function before surgery or certain medications

They can also be repeated over time to track changes in lung health.

Supporting Lung Health

Regardless of test outcomes, everyday habits can help support healthy lungs:

Avoid smoking and secondhand smoke
Stay physically active within your limits
Follow prescribed inhalers or treatments
Reduce exposure to air pollutants when possible

Overall, PFTs offer valuable insight into breathing health and help guide care in a clear, measurable way.

Sources

Association, American Lung. “Lung Function Tests.” American Lung Association, www.lung.org/lung-health-diseases/lung-procedures-and-tests/lung-function-tests. Accessed 20 Jan. 2026.

GL;, Haynes JM;Kaminsky DA;Ruppel. “The Role of Pulmonary Function Testing in the Diagnosis and Management of COPD.” Respiratory Care, U.S. National Library of Medicine, pubmed.ncbi.nlm.nih.gov/37353330/. Accessed 20 Jan. 2026.

Ponce, Mario C. “Pulmonary Function Tests.” StatPearls [Internet]., U.S. National Library of Medicine, 28 Aug. 2023, www.ncbi.nlm.nih.gov/books/NBK482339/.

professional, Cleveland Clinic medical. “Pulmonary Function Test: Purpose, Procedure & Results.” Cleveland Clinic, 9 Dec. 2025, my.clevelandclinic.org/health/diagnostics/17966-pulmonary-function-testing.

Pulmonary Function Tests | Johns Hopkins Medicine, www.hopkinsmedicine.org/health/treatment-tests-and-therapies/pulmonary-function-tests. Accessed 21 Jan. 2026.

Silva, Marta Carvalho, et al. “Pulmonary Function Tests: The Patient´s Perspective.” Pulmonology, U.S. National Library of Medicine, 2022, pmc.ncbi.nlm.nih.gov/articles/PMC8292038/.

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