The Diffusion Capacity Test measures how well oxygen and other gases pass from the lungs into the bloodstream. This test is often used to assess lung function and can help diagnose conditions like chronic obstructive pulmonary disease (COPD) or pulmonary fibrosis. During the test, a patient breathes in a small amount of a harmless gas, and the amount that enters the blood is measured. The results indicate how effectively the lungs transfer gases, providing valuable information about lung health. A lower diffusion capacity may suggest issues with the lung tissue or blood flow, while normal results typically indicate healthy lung function.