DLCO measures the total amount of carbon monoxide your lungs can transfer, while DLVA represents that transfer rate per unit of alveolar volume. If your DLCO is low but your DLVA remains within 90% of the predicted range, it often suggests a loss of lung volume rather than a primary membrane issue. We look at both metrics to pinpoint whether the challenge is related to lung size or the health of the alveolar-capillary interface. This distinction helps us provide a more accurate diagnosis.