Pulmonary function tests (PFTs) are noninvasive tests that show how well the lungs are working. The tests measure lung volume, capacity, rates of flow, and gas exchange. This information can help your healthcare provider diagnose and decide the treatment of certain lung disorders.

What can a PFT diagnose?

• asthma.
• chronic bronchitis.
• respiratory infections.
• lung fibrosis.
• bronchiectasis, a condition in which the airways in the lungs stretch and widen.
• COPD, which used to be called emphysema.
• asbestosis, a condition caused by exposure to asbestos.

What is the normal range for a pulmonary function test?

Pulmonary function testNormal value (95 percent confidence interval)TLC80% to 120%FRC75% to 120%RV75% to 120%DLCO> 60% to < 120%