A pulmonary function test (PFT) with reversibility test is spirometry performed before and after a bronchodilator to measure changes in lung function. It assesses airflow obstruction and helps distinguish reversible airway disease (like asthma) from fixed obstruction (like COPD). Key measures are FEV1 and FVC; a bronchodilator response is usually considered significant if FEV1 rises ≥12% and ≥200 mL, guiding diagnosis and treatment.

A PFT diffusion study (DLCO) measures how well gases move from the lung’s air sacs into the blood. During the test you inhale a tiny amount of carbon monoxide, hold your breath briefly, then exhale; lab analysis calculates gas transfer. It assesses gas-exchange efficiency, helping diagnose or monitor interstitial lung disease, emphysema, pulmonary vascular disease, and can be affected by anemia or smoking.

Pulmonary function tests fall into two main categories: (1) airflow measurements — spirometry and flow–volume loops that assess FEV1, FVC and obstructive patterns; and (2) lung volumes and gas-exchange tests — total lung capacity and residual volume measured by plethysmography/helium dilution, plus diffusing capacity (DLCO) to evaluate restriction and gas transfer.

In pulmonary function testing, diffusion refers to the lung’s ability to transfer gas from the alveoli into the blood, usually measured as DLCO (diffusing capacity for carbon monoxide). It reflects alveolar-capillary membrane surface area, membrane thickness, and pulmonary blood volume. Reduced diffusion occurs in emphysema, interstitial lung disease, pulmonary vascular disease and anemia; elevated values are uncommon.

Pulmonary function tests (PFTs) vary by country and setting: on the UK public system they’re provided free; private clinics typically charge about £40–£150. In India prices commonly range roughly ₹400–₹2,000. In the United States costs vary widely depending on complexity and insurance, roughly $100–$1,000 or more for a full panel. Exact fees depend on location, test type, and facility.

Yes. Pulmonary function tests (PFTs) detect abnormal lung function—reduced airflow, volumes, and gas transfer—which indicate lung damage from asthma, COPD, fibrosis, or vascular disease. A low DLCO suggests interstitial or vascular injury; obstructive or restrictive patterns point to different damage types. PFTs show functional impairment but not structural detail; imaging and clinical evaluation are needed to localize or confirm anatomic damage.