Supporting to diagnose interstitial lung disease & pulmonary fibrosis with a non-invasive method. Interstitial lung disease (ILD) is an umbrella term used for a large group of diseases that cause scarring (fibrosis) of the lungs. The scarring causes stiffness in the lungs which makes it difficult to breathe and get oxygen into the bloodstream. KL-6 can help diagnose and monitor lung damage from ILD from time to time with quantitative results.