Interstitial Lung Disease

Interstitial lung disease is a term for a group of over 200 conditions that cause inflammation and scarring in the lungs, making it harder to breathe and get enough oxygen into your body.

What is Interstitial Lung Disease?
Types and Examples
Affected Parts of the Lungs
Symptoms
Causes and Risk Factors
Diagnosis
Treatment
Possible Complications
Living With Interstitial Lung Disease
Outlook

ILD, diffuse parenchymal lung disease, DPLD

What is Interstitial Lung Disease?

Interstitial lung disease (ILD) is a term for a group of over 200 conditions that cause inflammation (swelling and irritation) and scarring in your lungs.^[1] ILD damages the tissues between the small air sacs in your lungs, called alveoli, and the blood vessels around them. This makes it harder for you to move oxygen out of your lungs and into your body.^[1]

When you have interstitial lung disease, parts of your lungs that help oxygen get into your blood and out to your tissues are damaged. Scarring in your lungs makes it hard to breathe, and you might have a chronic cough. Lack of oxygen can make you feel tired all the time.^[1]

The disease may get worse slowly or rapidly at a pace that often cannot be predicted. Once lung scarring occurs, it generally is not reversible.^[2] Treatment focuses on keeping more scarring from occurring, managing symptoms and making quality of life better.^[2]

Types and Examples

There are over 200 interstitial lung diseases. The most common is idiopathic pulmonary fibrosis, which means lung scarring without a known cause, followed by diseases caused by occupational exposures or connective tissue disorders.^[1]

A few examples of interstitial lung diseases include:^[1]

Asbestosis
Silicosis
Radiation pneumonitis
Nonspecific interstitial pneumonia
Hypersensitivity pneumonitis
Sarcoidosis

Not all ILD is pulmonary fibrosis (lung scarring). Pulmonary fibrosis is a type of interstitial lung disease, but the two terms are not the same.^[1]

Lungs
Alveoli (air sacs)
Lung interstitium (tissue between air sacs)
Airways
Blood vessels around air sacs

Affected Parts of the Lungs

In ILDs, scarring damages tissues in or around the lungs’ air sacs, or alveoli, and airways. The lung interstitium is the space between the air sacs and the small blood vessels that surround the air sacs. It contains connective tissue.^[4]

When you breathe, oxygen from the air passes through your air sacs and lung interstitium and into your blood. At the same time, carbon dioxide moves from your blood through the lung interstitium and into your air sacs.^[4]

If you have an ILD, your lung interstitium becomes thick and stiff. This makes it harder for oxygen to move out of the lungs and into the bloodstream and for carbon dioxide to move out of the bloodstream and into the lungs.^[4] As part of this process, lung tissue thickens and stiffens, making it hard for the lungs to expand and fill with air.^[2]

Symptoms

The main symptoms of interstitial lung disease are:^[2]

Shortness of breath at rest or shortness of breath that worsens with physical activity or exercise
Dry cough

Common symptoms of interstitial lung disease also include:^[1]

Fatigue (extreme tiredness)
Chest discomfort

Symptoms are usually mild at first but get worse over months or years. You may have additional symptoms depending on the underlying cause of ILD.^[1] Many people with ILD are short of breath with activity and may have a bothersome dry cough.^[2]

Causes and Risk Factors

The causes of interstitial lung disease are usually described as known or unknown. A known cause is when ILD happens because of a disease you’re living with or something you were exposed to, like certain medications, radiation or harmful substances. An unknown cause, also called idiopathic, is when you have ILD but you don’t have an underlying condition and haven’t been exposed to anything to cause it.^[1]

Known Causes

Known causes of interstitial lung disease include:^[1]

Connective tissue disease, including rheumatoid arthritis, lupus and scleroderma
Granulomatous disease, like sarcoidosis
Inhaling certain substances, like asbestos, silica, tobacco and beryllium
Some medications, including certain antibiotics, chemotherapy drugs, or heart medications
Radiation therapy to the chest

Long-term exposure to occupational or environmental agents can have a toxic effect on the lungs. Common agents are mineral dust (such as silica, asbestos, coal mine dust, beryllium, and hard metal), organic dust (including mold spores and aerosolized bird droppings), and toxic gases.^[5]

Who is at Higher Risk

You’re more likely to develop interstitial lung disease if you:^[1]

Are over 70 years old
Are male
Smoke or used to smoke
Have a history of certain illnesses or conditions, like hepatitis C, tuberculosis, pneumonia, COPD or connective tissue disease
Work around substances that can irritate your lungs, like asbestos, silica, molds, fungi or bacteria
Have had chest radiation

Diagnosis

Finding the cause of interstitial lung disease can be challenging, and sometimes the cause cannot be found. Many conditions fall into the category of ILD. Healthcare professionals must rule out other conditions before making a diagnosis.^[8]

Blood Tests

Certain bloodwork can detect proteins, antibodies and other markers of autoimmune diseases or inflammatory responses to environmental exposures, such as those caused by molds or bird protein.^[8]

Imaging Tests

Computerized tomography, also called a CT scan, is a key imaging test for the diagnosis of interstitial lung disease. It’s sometimes the first test in the diagnosis. CT scanners produce 3D images of internal structures. A high-resolution CT scan can be especially helpful in figuring out how much lung damage there is. It can show details of the scarring, which can help narrow the diagnosis and guide treatment decisions.^[8]

An echocardiogram uses sound waves to visualize the heart. It can create still images of your heart’s structures and videos that show how your heart is working. This test can measure the amount of pressure in the right side of your heart.^[8]

Pulmonary Function Tests

These tests require you to breathe out quickly and forcefully through a tube connected to a machine. The machine measures how much air your lungs can hold and how quickly air moves in and out of your lungs.^[8]

Other Tests

Your doctor may also perform bronchoscopy, a procedure where a thin tube with a camera is inserted through your nose or mouth into your lungs to examine the airways and collect tissue samples. In some cases, a surgical lung biopsy may be necessary to obtain a larger tissue sample for diagnosis.^[8]

Treatment

Treatment for ILDs does not cure your lung damage, but it can prevent lung damage from getting worse and can help you breathe easier. Your treatment will depend on the cause of your condition and how serious your symptoms are.^[10]

Lifestyle Changes

If you smoke, the most important thing you can do is quit smoking. You should also avoid secondhand smoke and places where other lung irritants are present as much as possible. These include spaces where dust, strong odors, allergens and toxins may be present in the air.^[12]

Physical activity can help to strengthen the muscles used in breathing and improve your overall wellness. Your doctor can help determine what kinds of activity are safe for you.^[12]

Your doctor may recommend pulmonary rehabilitation, which encompasses a variety of methods designed to improve the well-being of people with chronic breathing problems. Rehab may include an exercise program, training in managing ILD, nutritional counseling and psychological counseling.^[12]

Medicines

Depending on the type of ILD you have, your doctor may prescribe medicine to help you breathe easier. These medicines work in different ways:^[10]

Bronchodilators can relax the muscles around your airways. This helps open your airways and makes breathing easier.
Corticosteroids (inhaled or oral) can help treat inflammation in your lungs and reduce the immune system activity that causes scarring in some forms of ILD.
Antifibrotics (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.
Immunomodulators are therapies that alter the body’s immune response.
Antibiotics treat respiratory infections that can worsen ILD.

Oxygen Therapy

If you have trouble breathing or low oxygen levels in your blood, you may need oxygen therapy. This treatment delivers extra oxygen through a mask or small tubes placed in your nose to help you breathe more easily.^[10]

Lung Transplant

Lung transplant is an option for some people who have ILD. This may be considered when other treatments are no longer working.^[2]

Possible Complications

When damage continues to get worse, you can have life-threatening complications, like lung infections and respiratory failure (not enough oxygen or too much carbon dioxide in your body).^[1]

Without treatment, ILDs may cause the following complications:^[13]

Collapsed lung (pneumothorax)
Frequent lung infections
High blood pressure in your lungs (pulmonary hypertension) caused by scar tissue in the lungs’ arteries
Right-sided heart failure, which is often a result of pulmonary hypertension
Lung cancer
In children, problems growing

Living With Interstitial Lung Disease

If you have an ILD, it is important to continue your treatment plan. Talk to your healthcare provider about how often you need check-ups and how to monitor your condition.^[13]

Managing Your Condition

Your doctor may ask you to take the following steps to help avoid complications:^[13]

Avoid substances in your environment that can make your ILD worse
Get routine follow-up care, including repeated lung tests to see whether your lung damage is getting worse
Tell your doctor if your symptoms get worse or if you get 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, including quitting smoking if you smoke
Get medical care for other health conditions that can make your lung damage worse

Coping Strategies

A diagnosis of ILD comes with feelings of anxiety and uncertainty about the future. As the condition progresses, patients may struggle to perform normal daily activities and begin limiting social interactions. Levels of depression are often high among ILD sufferers.^[15]

Practicing good self-care includes maintaining a healthy lifestyle, having good sleep habits, stopping smoking, taking medication as directed and attending clinic appointments when necessary. Engaging in regular physical exercise can benefit patients both physically as well as giving them a sense of achievement which can positively influence their mental well-being.^[15]

Relaxation techniques including breathing exercises can help ILD patients cope by helping relieve symptoms of breathlessness. Some breathing techniques that may be helpful include pursed-lips breathing, diaphragmatic breathing, and paced breathing.^[15]

If you have serious trouble breathing, call emergency services immediately.^[13]

Outlook

Since there are many kinds of interstitial lung diseases, any one case could be mild or very serious. Most kinds of ILD cause irreversible lung damage. The most serious ILDs are progressive, where your condition continues to worsen over time.^[1]

About 3 out of every 10,000 people in the United States are diagnosed with an ILD every year. ILDs can be mild, serious, or even life-threatening.^[4]

That said, early diagnosis and promising therapies can extend the lives of those with ILD. According to specialists, “ILD is no longer a death sentence by any stretch.” A trend toward earlier diagnosis, combined with FDA-approved medications and several other promising drugs now in clinical trials, are among the reasons for improved outcomes.^[16]