diffusion capacity of the lungs for carbon monoxide (DLCO)

The diffusion capacity of the lungs for carbon monoxide (DLCO) measures how effectively gases like oxygen can transfer from your lungs into your blood. During the test, a small amount of carbon monoxide is breathed in because it binds easily to hemoglobin. The test calculates how much of the gas is absorbed to assess the health of the lung's alveoli (air sacs) and blood vessels. A normal DLCO indicates good gas exchange, while a low result can suggest issues such as lung disease, thickened walls, or reduced blood flow affecting oxygen transfer.