What Is a PFT Test & Who Should Get One
Published on: Jul 22, 2026
TABLE OF CONTENTS
- What Is a Pulmonary Function Test (PFT)?
- Why Are Pulmonary Function Tests Performed?
- Types of Pulmonary Function Tests
- Who Should Get a PFT Test?
- Conditions That Can Be Diagnosed or Monitored with a PFT
- How to Prepare for a Pulmonary Function Test
- What Happens During a PFT Test?
- Understanding Your PFT Test Results
- Conclusion
- FAQs
- References
Breathlessness climbing stairs, a cough that won't quit, wheeze that flares with exertion - symptoms like these often lead a doctor to order a pulmonary function test before reaching for anything more invasive. The test measures exactly how well the lungs move air in and out, and how efficiently oxygen actually transfers into the bloodstream. India's TB burden and rising COPD rates linked to air pollution and tobacco use have made PFTs a routine part of respiratory workups across most major hospitals. [1]
What Is a Pulmonary Function Test (PFT)?
A PFT is a group of non invasive breathing tests that measure lung volume, airflow speed and gas exchange efficiency. The most common version of PFT is spirometry that has a patient breathe forcefully into a mouthpiece connected to a sensor, generating numbers that compare against predicted values for someone of the same age, height, sex and ethnicity. [2]
Why Are Pulmonary Function Tests Performed?
Doctors perform PFTs for several reasons:
To diagnose suspected lung conditions.
To track how an existing lung condition is progressing over time.
To check lung function before a surgery involving anaesthesia
To distinguish between obstructive conditions like asthma or COPD (where air struggles to leave the lungs) and restrictive conditions (where the lungs simply can't expand fully). [3]
Types of Pulmonary Function Tests
Different types of PFTs are:
Spirometry measures how much air a person can forcefully exhale and how fast
Trapped air inside the lungs gets measured through lung volume testing, often using a sealed booth
Diffusion capacity testing checks how efficiently oxygen crosses from the lungs into the blood
A bronchodilator response test sometimes follows spirometry (measuring lung function again after an inhaler) to see whether airway narrowing reverses, a pattern typical of asthma. [4]
Who Should Get a PFT Test?
Persistent cough, unexplained breathlessness, wheezing, or chest tightness lasting beyond a few weeks all need a PFT referral. Smokers past 40, anyone with long-term occupational dust exposure and patients being evaluated before major surgery also get a PFT test. [5]
Conditions That Can Be Diagnosed or Monitored with a PFT
Commonly diagnosed conditions are:
Obstructive diseases like asthma and COPD
Pulmonary fibrosis and other interstitial lung diseases
Occupational lung disease including silicosis among stone-cutting and quarry workers.
How to Prepare for a Pulmonary Function Test
Before a test:
Avoid heavy meals for at least two hours before the test
Smoking or using a hookah should stop several hours beforehand, ideally longer
Wearing loose clothing makes deep breathing considerably easier during the test
The doctor may ask certain inhalers to be skipped beforehand too, since these can mask the very airway narrowing the test is trying to detect.
What Happens During a PFT Test?
A clip on the nose forces breathing through the mouth alone, sealed tightly around a mouthpiece connected to the spirometer. Several rounds of forceful inhaling and exhaling follow, each repeated a few times to confirm consistent, reliable readings. The whole process feels effortful but causes no pain and some people find the forceful breathing tiring, nothing more.
Understanding Your PFT Test Results
Results compare against predicted normal values, expressed as a percentage. Generally 80% or above counts as normal. Lower numbers point toward obstruction or restriction depending on which specific measurements drop. A pulmonologist interprets the full pattern together.
Conclusion
Breathing changes beyond what a passing cold explains deserve a conversation with a doctor about whether a PFT makes sense. The test is quick, safe and often clarifies a diagnosis that symptoms alone leave genuinely unclear.
FAQs
Do I need a PFT test if I only have occasional shortness of breath?
Worth mentioning to a doctor regardless of frequency, particularly if it's new or worsening. Occasional symptoms sometimes still reflect early airway changes a PFT can pick up before they become constant.
Is a PFT test painful or uncomfortable?
No pain involved but just effort. The forceful breathing required can feel tiring or briefly lightheaded for some people but the sensation passes within seconds of each attempt.
How long does a pulmonary function test take?
Basic spirometry takes about 15 to 30 minutes. Adding lung volume or diffusion capacity testing extends the full visit closer to 45 minutes to an hour.
Can I eat or drink before a PFT test?
A light meal is fine; a heavy one isn't since a full stomach makes deep forceful breathing harder. Avoiding caffeine beforehand is also commonly advised, as it can affect airway measurements slightly.
Should I stop using my inhaler before the test?
Sometimes, depending on what the doctor is checking for as skipping a dose can reveal underlying airway narrowing more clearly. Always follow the specific instructions given.
Can a PFT detect asthma even if I'm not having symptoms during the test?
It can though a normal result during a symptom-free period doesn't fully rule asthma out. A bronchodilator response test or additional challenge testing sometimes catches what a single quiet-day reading misses.
Is a PFT test safe for older adults and children?
Yes with techniques adjusted for age - younger children sometimes need simplified versions since the standard test requires forceful, sustained cooperation that's harder for them to manage.
What does it mean if my PFT results are abnormal?
Abnormal results point toward obstruction, restriction or occasionally both, but they don't diagnose a specific condition alone. A pulmonologist combines the pattern with symptoms, history and sometimes imaging to reach a diagnosis.
How often should I undergo a pulmonary function test?
Depends entirely on the underlying condition. Stable asthma might need annual checks while progressive conditions like pulmonary fibrosis often need testing every few months to track decline.
Can I return to work or normal activities immediately after the test?
Yes immediately. The test has no lingering physical effect beyond occasional brief tiredness from the forceful breathing and there's no recovery period required.
References
1. Salvi SS, Barnes PJ. Chronic obstructive pulmonary disease in non-smokers. Lancet. 2009;374(9691):733–743. DOI: 10.1016/S0140-6736(09)61303-7
https://doi.org/10.1016/S0140-6736(09)61303-7
2. Miller MR, et al. Standardisation of spirometry. Eur Respir J. 2005;26(2):319–338. DOI: 10.1183/09031936.05.00034805
https://doi.org/10.1183/09031936.05.00034805
3. Pellegrino R, et al. Interpretative strategies for lung function tests. Eur Respir J. 2005;26(5):948–968. DOI: 10.1183/09031936.05.00035205
https://doi.org/10.1183/09031936.05.00035205
4. Busse WW, Lemanske RF Jr. Asthma. N Engl J Med. 2001;344(5):350–362. DOI: 10.1056/NEJM200102013440507
https://doi.org/10.1056/NEJM200102013440507
5. Celli BR, MacNee W; ATS/ERS Task Force. Standards for the diagnosis and treatment of patients with COPD: a summary of the ATS/ERS position paper. Eur Respir J. 2004;23(6):932–946. DOI: 10.1183/09031936.04.00014304
https://doi.org/10.1183/09031936.04.00014304
6. Quanjer PH, et al. Multi-ethnic reference values for spirometry for the 3–95 year age range: the Global Lung Function 2012 equations. Eur Respir J. 2012;40(6):1324–1343. DOI: 10.1183/09031936.00080312
