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Interstitial Lung Disease (ILD)

Interstitial Lung Disease (ILD) is a general term that includes a variety of chronic lung disorders. When a person has ILD, the lung is affected in three ways. First, the lung tissue is damaged in some known or unknown way. Second, the walls of the air sacs in the lung become inflamed. Finally, scarring (or fibrosis) begins in the interstitium (or tissue between the air sacs), and the lung becomes stiff.

Breathlessness during exercise can be one of the first symptoms of these diseases. A dry cough also may be present. These are common symptoms that many people ignore. Someone with these symptoms may wait until they feel quite ill before going to the doctor.

People with different types of ILD may have the same kind of symptoms but their symptoms may vary in severity. Their chest X-rays may look alike. Further testing is usually recommended to identify the specific type of ILD a person has. Some ILDs have known causes and some (idiopathic) have unknown causes.

The tissue between the air sacs of the lungs is called the interstitium. Interstitial lung disease is named after this tissue because this is the tissue affected by fibrosis (scarring). Interstitial lung disease is sometimes also known as “interstitial pulmonary fibrosis.” The terms interstitial lung disease, pulmonary fibrosis and interstitial pulmonary fibrosis are often used to describe the same condition.

The course of these diseases is unpredictable. If they progress, the lung tissue thickens and becomes stiff. The work of breathing then becomes more difficult and demanding. Some of the diseases improve with medication if treated when inflammation occurs. Some people may need oxygen therapy as part of their treatment.

The diseases may run a gradual course or a rapid course. People with ILD may notice variations in symptoms—from very mild to moderate to very severe. Their condition may remain the same for long periods of time or it may change quickly. It’s important to stay in touch with your doctor and report any changes in symptoms. You and your doctor can work together to manage ILD.


While the progress and symptoms of these diseases may vary from person to person, there is one common link between the many forms of ILD. They all begin with an inflammation. The inflammation may affect different parts of the lung, as explained below:

  1. The walls of the bronchioles (small airways). When inflammation involves the bronchioles, it is called bronchiolitis.
  2. The walls and air spaces of the alveoli (air sacs). When inflammation involves the alveoli, it is called alveolitis.
  3. The small blood vessels (capillaries) of the lungs. When inflammation involves the small blood vessels, it is called vasculitis.

Inflammation of these parts of the lung may heal or may lead to permanent scarring of the lung tissue. When scarring of the lung tissue takes place, the condition is called pulmonary fibrosis.

Fibrosis, or scarring of the lung tissue, results in permanent loss of that tissue’s ability to transport oxygen. The level of disability that a person experiences depends on the amount of scarring of the tissue. This is because the air sacs, as well as the lung tissue between and surrounding the air sacs, and the lung capillaries, are destroyed by the formation of scar tissue. If this happens, your doctor may prescribe oxygen to help you breathe easier.


Several causes of pulmonary fibrosis are known. They include:

  1. Occupational and environmental exposures.Many jobs – particularly those that involve mining or that expose workers to asbestos or metal dusts—can cause pulmonary fibrosis. Workers doing these kinds of jobs may inhale small particles (like silica dusts or asbestos fibers) that can damage the lungs, especially the small airways and air sacs, and cause scarring (fibrosis). Agricultural workers also can be affected. Some organic substances, such as moldy hay, cause an allergic reaction in the lung. This reaction is called Farmer’s Lung and can cause pulmonary fibrosis. Other fumes found on farms are directly toxic to the lungs.
  1. Sarcoidosis.A disease characterized by the formation of granulomas (areas of inflammatory cells), which can attack any area of the body but most frequently affects the lungs.
  2. Drugs.Certain medicines may have the undersirable side effect of causing pulmonary fibrosis. Check with your doctor about the medicines you are taking and ask about any possible side effects.
  3. Radiation.(treatment for breast cancer)
  4. Connective tissue or collagen diseasessuch as rheumatoid arthritis and systemic sclerosis.
  5. Genetic/familial.This is not as common as the other causes listed.


When all known causes of interstitial lung disease have been ruled out, the condition is called “idiopathic” (of unknown origin) pulmonary fibrosis (IPF).

There are several theories as to what may cause IPF; including viral illness and allergic or environmental exposure (including tobacco smoke). These theories are still being researched. Bacteria and other microorganisms are not thought to be the cause of IPF.

There is also a familial form of the disease, known as familial idiopathic pulmonary fibrosis. Additional research is being done to determine whether there is a genetic tendency to develop the disease, as well as to determine other causes of IPF.


Shortness of breath is the main symptom of idiopathic pulmonary fibrosis. Since this is a symptom of many types of lung disease, making the correct diagnosis may be difficult. The shortness of breath may first appear during exercise. The condition then may progress to the point where any exertion is impossible. If the disease progresses, the person with IPF eventually may be short of breath even at rest. Other symptoms may include a dry cough (without sputum). When the disease is severe and prolonged, heart failure with swelling of the legs may occur.


A very careful patient history is an important tool for diagnosis. The history will include environmental and occupational factors, hobbies, legal and illegal drug use, arthritis, and risk factors for diseases that affect the immune system. A physical examination, chest X-ray, pulmonary function tests, and blood tests are important. These tests will help your doctor rule out other lung diseases and determine the extent of disease.

Bronchoalveolar lavage (BAL)—a test which permits removal and examination of cells from the lower respiratory tract—may be used to diagnose IPF: this test helps a doctor identify inflammation in lung tissue, and also helps exclude infections and malignancies (cancer) as a cause of a patient’s symptoms. The test is done during bronchoscopy, a special examination of the lung.

Lung biopsy —Either done during bronchoscopy or as a surgical procedure that removes a sample of lung tissue for your doctor to study—this procedure is usually required for diagnosis of IPF.


Diagnostic Tests That May Be Used to Identify Pulmonary Fibrosis or Interstitial Lung Disease

  1. 1. Blood Tests
  2. Pulmonary Function Tests
  3. Chest X-ray
  4. CT Scan
  5. Bronchoscopy
  6. Bronchoalveolar Lavage
  7. Lung Biopsy
  8. CT Scan


Corticosteroids may be administered to treat the inflammation present in some people with IPF. The success of this treatment for many forms of pulmonary fibrosis is variable and is still being researched. Other drugs are occasionally added when it is clear that the steroids are not effective in reversing the disease.Some doctors may use corticosteroids in combination with other drugs when the diagnosis is first established. Which drug treatment plan is effective, and how long to use the drugs is the focus of current research.

Oxygen therapy may be prescribed for some people with IPF. The need for oxygen will be determined by your doctor and may depend on the severity of disease, as well as your activity level. Talk with your doctor if you think you may need oxygen or if you have concerns about oxygen.

Influenza vaccine and pneumococcal pneumonia vaccine are both recommended for people with IPF or any lung disease. These two shots may help prevent infection and keep you healthy. Lung transplantation may offer hope for selected people with severe IPF and other lung diseases. Speak with your doctor about eligibility criteria for lung transplant recipients. Rehabilitation and education programs may help some people with IPF. Local support groups have been of benefit for people with IPF and their family members and friends.