The condition causes people to feel breathless, and it is often accompanied by a dry cough. Diagnosis can be challenging, and there is currently no cure for the disorder.
There are treatment options that can help with management of the symptoms, however. Treatment also includes lifestyle changes to slow progression, as much as possible.
- Causes range from environmental exposures to long-term medical conditions and genetic factors.
- The precise cause of most interstitial lung disease is unknown.
- As the disease progresses, it can lead to serious, potentially life-threatening complications.
Interstitial lung disease includes types such as interstitial pneumonia, idiopathic pulmonary fibrosis, and sarcoidosis.
There are many types of interstitial lung disease, all affecting the interstitium, which is the network of tissue running through both lungs.
The interstitium supports the alveoli or tiny air sacs in the lungs. Blood vessels flow through the interstitium, allowing the blood to receive oxygen and get rid of excess carbon dioxide.
Disorders that affect the interstitium thicken its tissues by scarring, inflammation and fluid retention. This thickening makes it difficult for the blood to absorb oxygen, which can lead to the symptoms of interstitial lung disease, such as breathlessness.
According to the American Thoracic Society, there are more than 200 different lung disorders that affect the interstitium. Some of these disorders include:
- Chronic silicosis: A lung diseased usually linked to a person's employment and caused by breathing in too much silica dust.
- Interstitial pneumonia: A lung infection occurring within the interstitium.
- Coal worker's pneumoconiosis: Also called black lung, this is a lung disorder caused by inhaling coal dust.
- Idiopathic pulmonary fibrosis: Chronic scarring in the interstitium with no known cause.
- Siderosis: Inflammation or scar tissue from inhaling iron from welding or mining.
- Nonspecific interstitial pneumonitis: Damage to the interstitium that often occurs with autoimmune conditions, such as scleroderma or rheumatoid arthritis.
- Hypersensitivity pneumonitis: Inflammation due to inhaling allergens or irritating substances, such as mold, plant and animal detritus, or chemicals.
- Connective tissue-related pulmonary fibrosis: A condition that affects some people with other connective tissue disorders, such as scleroderma or rheumatoid arthritis.
- Cryptogenic organizing pneumonia: Interstitial lung disease that can resemble pneumonia without an infection being present.
- Acute interstitial pneumonitis: Sudden damage to the interstitium that is severe and often requires emergency medical treatment and life-support.
- Desquamative interstitial pneumonitis: Significant inflammation of the lungs often associated with heavy smoking.
- Sarcoidosis: An inflammatory condition that affects the interstitium, sarcoidosis can also cause swollen lymph nodes and issues with the heart, eyes, joints, skin, and nerves.
- Familial pulmonary fibrosis: A buildup of scar tissue in the lungs that affects two or more people in the same family.
- Asbestosis: Scar tissue or inflammation in the lungs caused by inhaling asbestos fibers.
What are the symptoms?
Symptoms of interstitial lung disease vary and depend on the underlying cause. However, some symptoms are usually common to all the different forms of the disease. The most common symptom is a feeling of shortness of breath or not being able to catch the breath.
Most people with interstitial lung disease experience this symptom, and it may get worse with time. Eventually, a person with interstitial lung disease may feel out of breath even at rest.
This characteristic breathlessness is often accompanied by a dry, unproductive cough. Some people may also experience unexplained weight loss.
Anyone who is having trouble breathing should see their doctor for a diagnosis.
Causes and risk factors
Anyone can develop interstitial lung disease, though it may be more common in people with certain medical conditions, specific drug use, or environmental hazards. These risk factors may include:
Some autoimmune disorders cause the body to attack and damage the lungs and other organs.
Autoimmune diseases that may affect the lungs include:
- rheumatoid arthritis
- Sjögren syndrome
- mixed connective tissue disease
Exposure to toxins such as coal may damage the lungs over time.
Some lines of work may also put a person at risk for interstitial damage. Exposure to different toxins or pollutants can damage the lungs over time. These substances can include:
- dust, such as grain dust
- silica dust
- iron welding
- some animal proteins, such as those in bird droppings
- clay minerals, for example, talc
- radiation treatments
Some medications and drugs may also damage the lungs, including:
- heart medications used to treat irregular heartbeats
- certain antibiotics
- anti-inflammatory drugs
- chemotherapy drugs
- narcotics, including heroin and the medicinal treatment methadone
Complications may include:
Respiratory failure occurs in late-stage interstitial lung disease when extremely low blood oxygen levels can contribute to other organ failures.
Scar tissue, inflammation or low oxygen levels that restrict the flow of blood are causes of high blood pressure in the arteries of the lungs.
Right ventricle heart failure
Interstitial lung disease may lead to cor pulmonale when the right ventricle has to pump harder to move blood through the lungs. This extra work can cause the heart to fail due to the strain.
A doctor may recommend a CT scan to help diagnose interstitial lung disease.
If doctors think a person has interstitial lung disease, a simple imaging test, such as an X-ray or CT scan can help them assess the extent of the damage. They may also ask for other tests to help confirm their diagnosis.
A stress test can help doctors determine if a person's breathing symptoms are due to problems with the heart or with the lungs.
Stress tests increase the work of the heart by making a person exercise on a treadmill or take medications that cause the heart to beat faster.
Pulmonary function tests check for decreased lung capacity by having someone blow into a machine called a spirometer. The tests help determine what type of lung problem they may be experiencing. They also give information about how the lungs move air in and out and how well they use oxygen.
A bronchoscopy is another test to help doctors check the lung tissue itself. The doctor will lightly sedate the individual and put a tube down their throat and into the lungs. They will then remove a small bit of lung tissue for testing.
A bronchoalveolar lavage test can give additional information by the use of a saline rinse to collect cells for testing.
In some cases, however, a surgical biopsy may be necessary.
What are the treatment options?
There are currently no treatments that can completely reverse lung damage. But some treatments that are currently available may slow the progression of scarring and allow a person to breathe more freely.
Doctors may prescribe a few different treatments to manage someone's symptoms.
Many doctors recommend going through pulmonary rehabilitation, as this may help strengthen the lungs. Pulmonary rehabilitation uses various exercises to encourage a person to stretch their lung capacity and breather better.
A recent small study looked at the usefulness of pulmonary rehabilitation in people with interstitial lung disease due to different causes. The research concluded that pulmonary rehabilitation was beneficial for exercise tolerance, symptoms of interstitial lung disease and quality of life.
Oxygen therapy may be prescribed to help reduce how breathless a person feels and to improve their ability to be active. However, a recent review of the research questions the usefulness of oxygen therapy long-term in those with interstitial lung disease.
While some anti-inflammatory drugs can damage the lungs, others may help relieve symptoms. An example is the corticosteroid prednisone.
Corticosteroid treatment can be useful for a variety of interstitial lung disease, but it is not without side effects.
Immune suppressing drugs
If an autoimmune disorder is causing symptoms, doctors may recommend immune-suppressing drugs to reduce the damage occurring in the lungs.
A newer class of medications known as antifibrosis, or anti-scarring medications, seem to work by blocking the pathways in the body that are necessary for scar tissue formation.
These drugs have been approved for the treatment of idiopathic pulmonary fibrosis, a type of interstitial lung disease without a known cause.
Examples of these medications include Ofev (nintedanib) and Esbriet (pirfenidone), which are currently being studied for their effectiveness in other types of interstitial lung disease.
Conditions that are severe or progressing rapidly may require a lung transplant. Doctors will want to be sure that a person is in good enough health and free from other health issues before recommending a lung transplant.
The outlook for interstitial lung disease is different for everyone. It is a progressive disease, and there is currently no cure for damage caused by scarring and inflammation. Symptoms may progress unpredictably and make someone's life difficult.
People with interstitial lung disease may respond well to lifestyle changes, such as oxygen therapy, pulmonary rehabilitation, and eating a healthful and varied diet. Medical treatments may help slow lung damage and help someone breathe, and in some cases, a lung transplant will be a necessity.
Visiting a doctor to diagnose interstitial lung disease and to discuss the ideal treatment option is the best course of action for anyone who suspects they may be experiencing interstitial lung disease.