PFT Test: Pulmonary Function Test, Procedure and What Affects the Price

A PFT test, or Pulmonary Function Test, is a set of standardised breathing assessments that measure different aspects of how the lungs are functioning. It checks how much air can be moved in and out of the lungs, how quickly that movement occurs, and how effectively gas exchange takes place between the lungs and the bloodstream.

A complete pulmonary function test comprises three core components: spirometry, lung volume measurement, and diffusion capacity testing. Depending on the clinical indication, a doctor may order only one component or the full battery.

Understanding which components are included is important both for interpreting results and for understanding the cost of the test.

Spirometry measures the mechanics of airflow. The patient exhales as forcefully and completely as possible into a mouthpiece connected to a spirometer.

The two most clinically significant values produced are the Forced Vital Capacity (FVC), the total volume of air exhaled during a maximal effort, and the Forced Expiratory Volume in one second (FEV1), the volume exhaled in the first second of that effort.

The FEV1 to FVC ratio is the primary indicator used to distinguish obstructive lung disease from restrictive lung disease.

Lung volume measurement quantifies the total amount of air the lungs can hold, including the residual volume that remains after a full exhalation and cannot be expelled. Body plethysmography, performed inside a sealed booth, is the most accurate method.

This component is essential for diagnosing restrictive conditions such as pulmonary fibrosis, where total lung capacity is reduced even when airflow appears normal on spirometry.

Diffusion capacity testing (DLCO) measures how efficiently a small, safe concentration of carbon monoxide transfers from the air spaces of the lungs into the bloodstream. Because carbon monoxide behaves similarly to oxygen in this regard, DLCO is the most sensitive available indicator of gas exchange efficiency.

It is particularly informative for assessing emphysema, interstitial lung disease, and the pulmonary effects of systemic conditions.

A cardiopulmonary exercise test (CPET) may be added when the clinical question involves how well the lungs and heart perform under physical exertion rather than at rest.

A PFT test is indicated when a clinical picture involves the respiratory system and requires objective, quantified evidence of lung function rather than symptom assessment alone.

Common indications include unexplained breathlessness or exercise intolerance that has persisted for more than a few weeks, a chronic cough without an identified cause, wheezing that has not resolved with standard treatment, and initial diagnosis or ongoing monitoring of asthma, COPD, or pulmonary fibrosis.

PFT testing is also standard before certain surgical procedures where the patient's lung function determines anaesthetic risk and recovery capacity.

For employees in occupations involving dust, chemical fume, or industrial gas exposure, baseline and serial PFT testing is used to detect early occupational lung disease before symptoms develop.

The test is performed in a pulmonary function laboratory or a diagnostic centre equipped with a spirometer and, where required, a plethysmography booth.

The procedure begins with a nose clip placed over the nostrils to ensure all breathing occurs through the mouth and into the measuring device. The patient inhales fully, seals the lips around the mouthpiece, and then exhales as hard and fast as possible for as long as possible. This maximal exhalation is the spirometry manoeuvre.

It is repeated a minimum of three times to produce consistent, reproducible results, with brief rest periods between each attempt.

If lung volume measurement is included, the patient enters a sealed, clear-walled plethysmography booth and breathes against a closed shutter while pressure changes are measured to calculate total lung capacity and residual volume.

For diffusion capacity testing, the patient inhales a small concentration of carbon monoxide and a tracer gas, holds the breath for ten seconds, then exhales into a collection device. The proportion of carbon monoxide absorbed during the breath-hold is calculated to derive the DLCO value.

If a bronchodilator response test is included, spirometry is repeated approximately fifteen minutes after the patient inhales a short-acting bronchodilator. Significant improvement in FEV1 following the bronchodilator supports a diagnosis of reversible airway obstruction consistent with asthma.

The complete test takes between 30 and 90 minutes depending on which components are ordered.

PFT test pricing in India is not fixed and varies across several factors. Quoting a single number without knowing the specific components, facility, and city would not be accurate.

Components ordered have the most significant effect. A basic spirometry test is substantially less expensive than a full PFT, including lung volumes and diffusion capacity. Adding a bronchodilator response test or CPET increases the cost further.

Facility type affects pricing. Specialist pulmonology centres, tertiary hospitals, and established diagnostic chains price their testing differently from smaller general diagnostic labs. Equipment calibration standards and the availability of trained respiratory technicians also factor into the fee structure.

City and location influence pricing, with metropolitan centres typically reflecting higher operational costs.

Confirming the exact components prescribed by the doctor before comparing prices across facilities avoids the common error of comparing a basic spirometry quotation against a full PFT quotation.

Diagnostics: 8,500+ NABL-Accredited Labs: Employees can book a PFT test cashlessly through Visit Health’s broader partner network of 8,500+ NABL-accredited labs across India. Results are tracked digitally in the app, eliminating the need for physical report collection.

Teleconsultation: Pulmonology and Internal Medicine: PFT results, including FEV1-to-FVC ratios, DLCO values, and lung volume measurements, require specialist interpretation to translate into a clinical diagnosis and management plan. Visit Health's teleconsultation platform connects employees with pulmonologists and internal medicine specialists across 30+ specialities, same day, without a hospital visit or a separate referral chain.

AI-Powered Smart Reports: PFT reports list multiple values, including FVC, FEV1, FEV1/FVC ratio, TLC, RV, and DLCO, that most patients cannot interpret without clinical context. Visit Health's Smart Reports to convert these findings into plain-language summaries explaining what each value indicates and what the recommended next step is.

Visit Clinic: Bengaluru (Marathahalli, Outer Ring Road): For employees in Bengaluru who need an in-person pulmonology consultation or a referral for advanced respiratory investigation following PFT findings, Visit Clinic provides on-ground appointments connected into the broader diagnostic and specialist ecosystem.

A PFT test provides objective, quantified evidence of how the lungs are functioning across three distinct dimensions: airflow mechanics, total lung capacity, and gas exchange efficiency. These measurements are what allow a pulmonologist to distinguish obstructive from restrictive disease, confirm or exclude reversible airway obstruction, and track whether a lung condition is stable or progressing over time.

What does a PFT test check? 

How well the lungs move air in and out (spirometry); how much air they can hold, including residual volume (lung volumes); and how efficiently oxygen transfers from the lungs into the blood (diffusion capacity).

Is a PFT test painful? 

No. It involves breathing into a mouthpiece or sitting in a small sealed booth. Some patients find the maximal exhalation effort tiring, but no pain or discomfort is involved.

How long does a PFT test take? 

Between 30 and 90 minutes depending on which components are ordered. Basic spirometry alone takes approximately 15 to 30 minutes.

What is the difference between spirometry and a full PFT? 

Spirometry measures airflow and exhaled volume only. A full PFT adds lung volume measurement via plethysmography and diffusion capacity testing, providing a substantially more complete picture of respiratory function.

What should be avoided before a PFT test? 

Smoking for at least four hours before the test, heavy meals immediately before the appointment, and strenuous exercise on the day of testing. Specific instructions about bronchodilator medications should be confirmed with the ordering doctor.

What factors affect PFT test price? 

The components include the facility type, the city, and whether a bronchodilator response test is part of the protocol. Confirming the exact components ordered before requesting a quote avoids inaccurate price comparisons.

Can a PFT test diagnose asthma or COPD? 

It can identify obstructive and restrictive patterns that are characteristic of these conditions. Diagnosis is made by the clinician using PFT results alongside symptoms, clinical history, and other investigations.

Can employees book a PFT test through Visit Health? 

Through Visit Health's OPD benefit, yes, cashlessly across 8,500+ NABL-accredited labs, with digital result tracking and same-day pulmonology teleconsultation for interpretation.

Get your PFT results explained by a pulmonologist the same day, not after a long wait. Book a cashless test or consult in person at Visit Clinic