Interstitial lung disease (ILD) refers to a group of disorders that damage the interstitium (the lung tissue between the air sacs known as the alveoli and the blood vessels). This damage interferes with the ability of the lungs to transport oxygen and carbon dioxide. There are over 200 different types of ILD that can cause the same pattern of injury - inflammation and scarring - in lung tissue. This article provides an overview of what ILD is, its causes, symptoms, diagnosis and treatment.
What is Interstitial Lung Disease?
The lungs contain millions of tiny air sacs called alveoli where oxygen exchange takes place between inhaled air and blood vessels in the lungs. Thin walls separate these air sacs and maintain the overall structure of the lung. The walls contain a mesh-like support structure made up of collagen and elastic fibers and cells that secrete molecules to keep the walls strong and thin. When Interstitial Lung Disease occurs, this supportive structure of the lung becomes inflamed or scarred, making it hard for the lungs to work effectively. This causes shortness of breath and a declining lung function over time. ILD can affect the interstitium of both lungs or just areas of one lung.
Causes of Interstitial Lung Disease
Some known causes of ILD include:
- Environmental exposures: Chemical fumes, vapors, dusts, or gases from toxic work environments can cause pneumoconiosis like asbestosis and silicosis.
- Connective tissue diseases: Rheumatoid arthritis, scleroderma and others can spread into the lungs and cause ILD.
- Genetic conditions: Rare genetic conditions like Hermansky-Pudlak syndrome and pulmonary fibrosis are genetically linked.
- Cigarette smoking: Smoking significantly increases the risk of developing ILD.
- Infections: Certain fungal and viral infections can infect the lung tissue and spread.
- Unknown causes: In many cases, no clear external cause is identified, possibly due to multiple genetic and environmental factors interacting together.
Symptoms of ILD
Some common symptoms of ILD include:
- Progressive shortness of breath with exertion: This gradually worsens over time as lung function declines.
- Dry, raspy cough: Does not produce phlegm or sputum.
- Fatigue: Due to decreased oxygen levels in the bloodstream.
- Finger clubbing: Enlarged and rounded finger tips often develop.
- Weight loss: Due to increased work of breathing.
- Wheezing: A whistling or squeaky sound heard on expiration.
- Chest tightness or discomfort.
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