PFT ( Pulmonary Function Test )

Normal PFTs are values near the patient’s predicted values for age, sex, height and ethnicity. FEV1 and FVC are typically ≥80% of predicted; the FEV1/FVC ratio is usually ≥70% (or above the lower limit of normal). Total lung capacity and DLCO are generally ≥80% predicted. Values below these suggest obstructive, restrictive, or gas-exchange impairment.

Before a pulmonary function test, avoid smoking, heavy meals and vigorous exercise for several hours; follow your clinic’s instructions about withholding bronchodilator inhalers (only if advised). Wear loose, comfortable clothing, bring a list of current medications and your inhalers, and arrive a little early. Rest and avoid caffeine beforehand so you can breathe normally during the test.

Pulmonary function test costs vary by country and test complexity. Basic spirometry typically costs about $50–$300 (US) or ₹500–3,000 (India); a full PFT (lung volumes, diffusion studies) can range $150–$800+ in the US. In the UK it's free under the NHS; private clinics charge roughly £50–£200. Insurance often lowers out‑of‑pocket expenses.

Pulmonary function testing typically takes 30–60 minutes for routine spirometry; bronchodilator testing adds about 10–20 minutes. Comprehensive testing (lung volumes and diffusion capacity) usually requires 45–90 minutes. Expect extra time for registration, instructions and repeat maneuvers. Overall duration varies with test complexity, patient cooperation and whether medications must be withheld before testing.

Yes. Pulmonary function tests (spirometry, lung volumes, diffusion capacity) detect functional lung damage by identifying airflow obstruction, restrictive patterns, reduced lung volumes, and impaired gas transfer (DLCO). They quantify severity, monitor progression and treatment response, but do not visualize anatomical changes—imaging (chest X‑ray or CT) is needed to show structural damage. PFTs guide diagnosis and management of lung disease.

Normal lung capacity increases from a few hundred millilitres in infants to about 1–2.5 litres in school‑age children, reaching near‑adult values during adolescence. Average total lung capacity in healthy adults is roughly 6 L for men and 4–4.5 L for women. Function peaks in the 20s–30s and then declines about 20–30 mL per year thereafter, varying by height, sex, and health.