Interstitial Lung Disease

Interstitial lung disease (ILD) refers to a group of diseases that result in scarring (fibrosis) of the lungs. This scarring makes breathing and obtaining sufficient oxygen for the bloodstream difficult. Lung damage from ILD is often irreversible and tends to worsen over time. A combination of environmental exposure, genetics and lifestyle habits causes ILD.

In ILDs, scarring harms tissues in or around the lungs’ air sacs (alveoli) and airways. The lung interstitium is the space between the air sacs and the small blood vessels surrounding them, which contains connective tissue. When you breathe, oxygen from the air passes through the air sacs and lung interstitium into your blood. At the same time, carbon dioxide moves from your blood through the lung interstitium and into your air sacs. In cases of ILD, the lung interstitium becomes thick and stiff, making it more difficult for oxygen to transfer from the lungs into the bloodstream and for carbon dioxide to move from the bloodstream into the lungs.

Interstitial lung diseases are caused by damage to your lungs from genetics, lifestyle habits, environmental factors, medications or other medical conditions. Exposure to dust or mold in the environment can cause some ILDs, including asbestos-related lung diseases and hypersensitivity pneumonitis.

When you inhale, air enters your airways and travels down into your air sacs in your lungs. Your air sacs are typically elastic, meaning their size and shape can change easily. They expand when air enters the lungs and contract to help expel air from the lungs.

When you injure your lungs, your body usually repairs and heals the damage. However, if the injury leads to an ILD, the healing process may fail over time. Your body can repair damaged lungs with scar tissue. Scar tissue can thicken and stiffen your air sacs, making it difficult for them to expand and contract properly, ultimately impairing the movement of oxygen from your lungs into your bloodstream. Additionally, the scarring impedes the exit of carbon dioxide from your bloodstream into your lungs, where it is exhaled. For some ILDs, such as idiopathic pulmonary fibrosis, the cause of this scarring is unknown.

The following conditions can damage your lungs and increase your risk of an ILD:

• Family history: You have a higher risk of ILDs if a close relative has or had an ILD. Mutations, or changes in your genes, can make you more likely to develop scar tissue in your lungs.
• Environment and occupation: Exposure to mold, chemicals or bacteria at work or in your environment can damage your lungs. Inhaling dust from mining and construction work over a long time can increase your risk of asbestos-related lung disease, which is a type of ILD.
• Lifestyle habits: Smoking can damage your lungs or make lung damage worse.
• Medicines: While rare, certain antibiotics, heart medications and chemotherapy drugs can increase your risk.
• Other health conditions: Conditions such as sarcoidosis, autoimmune diseases, connective tissue disorders and viral infections, including COVID-19, can damage the lungs.
• Gender: Some autoimmune diseases and connective tissue disorders that cause ILDs are more common in women.

There is no way to prevent ILDs caused by your genes. You can prevent some ILDs by quitting smoking and avoiding toxic substances in your home or work environment that may damage your lungs.

Doctors screen for interstitial lung diseases using a combination of clinical evaluation, imaging, pulmonary function testing (PFT) and, in some cases, invasive diagnostic procedures. They will begin with a thorough medical history followed by a physical exam. Next, pulmonary function tests may be performed to help assess the degree to which the disease has affected lung function. Imaging tests, blood tests and biopsies are also standard diagnostic tools.

Interstitial lung diseases can be mild, serious or even life-threatening. Symptoms of ILDs may include shortness of breath, dry cough, chest discomfort and extreme tiredness. Symptoms differ depending on the type of ILD and its severity. They can manifest quickly or slowly and get worse over time. Symptoms in children who have ILDs may be different from symptoms in adults.

Some individuals with ILDs may not have symptoms initially, but symptoms can develop as the disease progresses. Other symptoms include:

• Shortness of breath
• A dry cough
• Abnormal sounds when you breathe
• Chest pain and discomfort
• Extreme tiredness
• Clubbing, which is a widening and rounding at the ends of your fingers or toes, along with a downward sloping of the nails

Your healthcare provider will diagnose your ILD based on your symptoms, medical and family histories, risk factors and results from tests and procedures. You may need to see a pulmonologist who specializes in lung diseases.

Your physician may order one of these common diagnostic tests to help diagnose an ILD:

• Blood tests to look for signs of an infection or an autoimmune disease that can cause an ILD
• Lung tests, including imaging tests such as chest X-rays and computed tomography (CT) scans, which take pictures of your lungs
• Lung function tests that measure how much air you exhale or how much air your lungs can hold. These tests help your doctor see how well your lungs are working.
• Bronchoalveolar lavage (BAL) tests collect fluid from the lungs. The fluid is then analyzed for high levels of white blood cells and other immune cells, or for environmental substances that can cause lung scarring.
• Lung biopsies require a very small sample of your lung tissue, which is then checked to determine if it shows signs of inflammation, scarring or other changes that occur when you have an ILD.

Treatment for ILDs depends on the type and severity of symptoms. Your doctor may recommend that you avoid environmental substances that trigger your condition. While treatment does not repair the scarring in your lungs, addressing symptoms early can slow down or stop lung damage and improve your lung function.

If your ILD is caused by substances in your environment or at work, you will need to avoid these substances. If you smoke, your doctor will ask you to stop, as it can make your lung damage worse and can increase your risk. Depending on your type of ILD, your doctor may prescribe medication to help you breathe more easily. These medicines work in different ways:

• Bronchodilators can relax the muscles around your airways, helping to open them and make breathing easier. Most often, this medicine is taken using a device called an inhaler. Side effects may include dizziness, shakiness, headache and changes in sleep patterns.
• Corticosteroids can help treat inflammation in your lungs. You may take these with an inhaler or as a pill. Common side effects from inhaled corticosteroids include a hoarse voice or a mouth infection called thrush. A spacer or holding chamber on your inhaler can help avoid these side effects. Oral corticosteroids can have more side effects than inhaled corticosteroids because the medicine is absorbed outside the lungs.
• Antifibrotics, such as nintedanib and pirfenidone, can help slow down lung damage. These medicines block growth factors in cells that are involved in causing scarring in the lungs. You may need to take these pills each day. Side effects may include nausea, vomiting, fatigue, dizziness, digestive issues, decreased appetite, weight loss and sensitivity to light.

Oxygen therapy is a treatment that delivers oxygen gas for you to breathe. You can receive oxygen therapy through tubes placed in your nose, a face mask or a tube inserted into your trachea (windpipe). You may need oxygen therapy if your condition causes very low blood oxygen levels. This treatment can be administered for a short or extended period in a hospital, another medical setting or at home.

Pulmonary rehabilitation is a supervised program that includes exercise training, health education and breathing techniques for people who have certain lung conditions or lung problems due to other conditions, or after a lung transplant. Your healthcare provider may discuss pulmonary rehabilitation with you to help you breathe more easily and improve your overall quality of life.

Some cases may require a lung transplant, which is a surgery that removes and replaces a diseased lung with a healthy lung. Lung transplants improve quality of life and extend the lifespan for people with severe or advanced chronic lung conditions that do not respond to other treatments.

If you have an ILD, it is crucial to adhere to your treatment plan as prescribed by your medical team. Discuss with your healthcare provider how often you need check-ups and how to monitor your condition.

Your doctor may ask you to take the following steps to avoid complications with your condition:

• Avoid substances in your environment that can make your ILD worse.
• Get routine follow-up care. You may need repeated lung tests to see whether your lung damage worsens. Tell your doctor if your symptoms worsen or if you notice new symptoms.
• Get routine vaccines. Pneumococcal, flu (influenza), and COVID-19 vaccines can help prevent lung infections that can lead to more lung damage.
• Make healthy lifestyle changes. If you smoke, find support to help you quit, as smoking raises your risk of severe lung damage and lung cancer.
• Seek medical care for other health conditions that may exacerbate your lung damage.