Interstitial Lung Disease Illustration

Interstitial Lung Disease: Overview and Practice Questions

by | Updated: Apr 18, 2024

Interstitial lung disease (ILD) encompasses a diverse group of lung disorders that primarily affect the interstitium, the tissue and space that surrounds the alveoli (air sacs) of the lungs.

While the manifestations of these disorders can vary significantly, they all share a common thread: inflammation or fibrosis (scarring) of the lung tissue.

Such changes can drastically impair a person’s ability to breathe and oxygenate blood.

Understanding the causes, presentation, and management of ILD is critical, given its potential impact on morbidity and quality of life.

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What is Interstitial Lung Disease?

Interstitial lung disease (ILD) refers to a group of disorders that cause progressive scarring of lung tissue. This broad category of conditions affects the interstitium, which is the tissue and space around the alveoli (air sacs) in the lungs.

The inflammation or fibrosis (scarring) that characterizes ILD can interfere with oxygen transfer from the lungs to the bloodstream, leading to difficulty breathing and other respiratory symptoms.

Interstitial Lung Disease Vector Illustration


There are numerous types of ILD, each with its own cause, symptom profile, and progression rate.

Some of the more common forms of ILD include:

  • Idiopathic Pulmonary Fibrosis (IPF): A chronic, progressive form of lung disease characterized by fibrosis without a known cause.
  • Sarcoidosis: Granulomas (small lumps of immune cells) form in various organs, predominantly the lungs, leading to inflammation and scarring over time.
  • Hypersensitivity Pneumonitis: An allergic reaction to inhaled substances like mold or dust, which leads to inflammation of the lungs.
  • Occupational Lung Diseases: Examples include asbestosis, silicosis, and coal worker’s pneumoconiosis. They are caused by long-term exposure to certain irritants found in the workplace.
  • Connective Tissue Diseases: Some autoimmune diseases, like rheumatoid arthritis or systemic sclerosis, can affect the lungs leading to ILD.
  • Drug-induced ILD: Some medications can cause lung inflammation or fibrosis.


Interstitial lung disease has several known and unknown causes, including the following:

  • Connective tissue diseases
  • Autoimmune diseases
  • Malignancy
  • Drug-induced
  • Infections
  • Inhaled substances

ILD can occur secondary to certain connective tissue and autoimmune diseases such as sarcoidosis, rheumatoid arthritis, lupus, systemic sclerosis, and polymyositis.

It is also caused by the inhalation of toxic substances, such as asbestosis, silicosis, hypersensitivity pneumonitis, and other occupational and environmental toxins.

There are also certain drugs and medications also known for causing ILD. Some examples include antibiotics, chemotherapy drugs, and certain anti-arrhythmic agents.

Lastly, ILD is caused by certain infections, such as atypical pneumonia, RSV, tuberculosis, and coronavirus.

Signs and Symptoms

Interstitial lung disease is known for causing a number of signs and symptoms, including the following:

  • Shortness of breath
  • Chest discomfort
  • Fatigue
  • Nonproductive cough
  • Weight loss
  • Hypertension

Note: In general, these signs and symptoms typically develop slowly over several months.


The treatment for ILD varies depending on the patient’s symptoms. Some of the standard treatment methods include:

  • Oxygen therapy
  • Corticosteroid medications
  • Pulmonary rehabilitation
  • Lung transplantation

The treatment method may also vary depending on the specific cause. For example, if the cause is due to inhalation of a toxic substance, the best treatment would be to avoid the said substance.

If a specific medication is the known cause of ILD, the patient should stop taking said medication.

Interstitial Lung Disease Practice Questions

1. What does ILD stand for?
ILD stands for Interstitial Lung Disease. It’s an abbreviation that we’ll use throughout the remainder of this study guide.

2. Interstitial lung diseases are a diverse group of illnesses that can be organized into groups based on what?
They are organized based on related causes.

3. Interstitial lung diseases generally cause what?
They cause chronic, progressive dyspnea on exertion and a nonproductive cough.

4. What breath sounds are common with ILD?
Fine, inspiratory crackles

5. What is the most common chest radiograph finding in ILD?
Diffuse reticular or reticulonodular infiltrates with reduced lung volumes.

6. What are the PFTs like for a patient with ILD?
Pulmonary function testing usually reveals restrictive physiology and decreased diffusion capacity; however, other patterns may be seen.

7. What are the causes of ILD?
The causes most frequently occur from exposure (tobacco, hypersensitivity pneumonitis antigens, silica, asbestos), autoimmune dysfunction (sarcoidosis, connective tissue diseases), and abnormal injury healing (IPF).

8. What is the specific treatment for ILD depend upon?
It depends on the underlying disease and may consist of an immunosuppressive.

9. What is the most common treatment for interstitial lung disease?
A lung transplant

10. What is a common physical finding of ILD?
Bibasilar inspiratory dry crackles in the bases.

11. What is the classification of ILD based on?

12. What is the most effective way to diagnose ILD?
Open lung biopsy

13. How does ILD affect blood pressure?
Hypertension is a symptom of ILD.

14. What form of ILD is typically seen in 50 to 70-year-old men with progressive dyspnea and bibasilar crackles?
Idiopathic Pulmonary Fibrosis

15. What form of ILD presents with intermittent episodes of dyspnea and is seen in people who live on farms?
Hypersensitivity pneumonitis

16. What is the most important thing to find when diagnosing hypersensitivity pneumonitis?
The patient’s history and work history.

17. What does the diagnosis of drug-induced interstitial lung disease rely on?
The exclusion of all other processes.

18. What type of ILD is commonly seen in coal miners, potters, and drill workers?

19. What is the primary goal of ILD treatment?
To prevent irreversible lung damage

20. The term Interstitial Lung Disease (ILD) refers to a broad group of inflammatory lung disorders that are characterized by what?
Acute, subacute, or chronic inflammatory infiltration of the alveolar walls by cells, fluid, and connective tissue.

21. What are some other names for Interstitial Lung Diseases?
Diffuse interstitial lung disease, fibrotic interstitial lung disease, pulmonary fibrosis, or pneumoconiosis.

22. If left untreated, an inflammatory process in the lungs can progress to what?
Irreversible pulmonary fibrosis

23. What are the major pathologic or structural changes of the lungs associated with interstitial lung disease?
Destruction of the alveoli and adjacent pulmonary capillaries; fibrotic thickening of the respiratory bronchioles, alveolar ducts, and alveoli; granulomas, honeycombing, and cavity formation; fibrocalcific pleural plaques (with asbestos); bronchospasm and excessive bronchial secretions.

24. How is the acute stage of ILD characterized?
Edema and the infiltration of a variety of white blood cells in the alveolar walls and interstitial spaces.

25. How is the chronic stage of ILD characterized?
In addition to the inflammation and infiltration of numerous white blood cells, some fibroblasts may be present in the alveolar walls and interstitial spaces.

26. What can occur after the chronic stage of ILD?
Further interstitial thickening, fibrosis, granulomas, and in some cases, honeycombing and cavity formation.

27. The exposure to what organic materials can cause ILD?
Moldy hay, silage, moldy sugar cane, mushroom compost, barley, cheese, wood pulp, bark, dust, cork dust, bird droppings, and paint.

28. The exposure to what medications can cause ILD?
Antibiotics, anti-inflammatory agents, cardiovascular agents, chemotherapy agents, and illicit drugs.

29. What connective tissue diseases can lead to ILD?
Scleroderma, rheumatoid arthritis, Sjogren’s syndrome, systemic lupus erythematosus, and sarcoidosis.

30. The exposure to what irritant gases can cause ILD?
Chlorine, ammonia, and nitrogen dioxide.

31. What is idiopathic pulmonary fibrosis (IPF)?
A progressive inflammatory disease of an unknown cause that leads to varying degrees of fibrosis and honeycombing in severe cases.

32. What are two rare diseases that can lead to ILD?
(1) Lymphangioleiomyomatosis (LAM), and (2) Pulmonary Langerhans cell histiocytosis (PLCH).

33. Which two miscellaneous diffuse interstitial lung diseases involve recurrent pulmonary hemorrhage?
(1) Goodpasture’s syndrome, and (2) Idiopathic pulmonary hemosiderosis.

34. How is DLCO affected by interstitial lung disease?
IDL can result in an increase in DLCO.

35. What is expected during the physical examination of a patient with ILD?
An increased heart rate, blood pressure, and respiratory rate; cyanosis, digital clubbing, peripheral edema, venous distention, and a nonproductive cough.

36. What chest assessment findings can be expected with ILD?
Increased tactile and vocal fremitus, dull percussion note, bronchial breath sounds, crackles, pleural friction rub, and whispered pectoriloquy.

37. What could be found on a chest radiograph associated with ILD?
Bilateral reticulonodular pattern, irregularly shaped opacities, granulomas, cavity formation, honeycombing, and pleural effusion.

38. Why is the management of ILD so difficult?
Because there is often no specific cause.

39. What are the respiratory care treatment protocols for ILD?
Oxygen therapy, bronchopulmonary hygiene therapy, mechanical ventilation, pulmonary rehabilitation, research trials, lung transplantation, and palliative care.

40. What is idiopathic pulmonary fibrosis?
The formation of scar tissue in the connective tissue of the lungs without a known cause, resulting in severe chronic restrictive lung disease.

41. What is the definition of interstitial lung disease?
A group of respiratory disorders characterized by a dry, unproductive cough and dyspnea on exertion. The chest radiograph usually shows fibrotic infiltrates in the lower lobe.

42. What is occupational ILD?
Interstitial lung disease resulting from occupational exposure (e.g., asbestosis).

43. What is required to make a diagnosis of interstitial lung disease?
A lung biopsy is typically required to make a definitive diagnosis of interstitial lung disease.

44. What are the key diagnostic features of interstitial lung disease (ILD)?
The key diagnostic features of interstitial lung disease (ILD) include dyspnea at rest or with exertion; bilateral diffuse interstitial infiltrates on a chest radiograph, physiologic abnormalities of a restrictive lung defect, and histopathologic features of inflammation or fibrosis of the pulmonary parenchyma.

45. Which interstitial lung disease has an unknown cause?

46. What is used to identify the type and etiology of interstitial lung disease?
Physicians perform many different tests to determine if a patient has interstitial lung disease (ILD). However, the patient’s medical history is most valuable in determining the specific type and etiology.

47. A physician is examining a patient whom she suspects has a form of interstitial lung disease (ILD). The patient is a smoker and presents with dyspnea, cough, fever, chills, and night sweats. The physical exam reveals digital clubbing. What disease might the patient have?
Patients with interstitial lung disease present with many different symptoms; however, the most likely diagnosis is idiopathic pulmonary fibrosis (IPF).

48. A physician is examining the chest radiograph of a patient she suspects has a form of interstitial lung disease (ILD). The radiograph shows eggshell calcification. What disease might the patient have?
The appearance of eggshell calcification on a chest radiograph is almost always unique to silicosis.

49. What are the indications for surgical lung biopsy in patients whom physicians suspect interstitial lung disease (ILD)?
Indications for surgical lung biopsy include a patient younger than 65 years; a history of fevers, weight loss, and sweats; a history of hemoptysis; symptoms and signs of peripheral vasculitis; a history of pneumothorax; a normal chest radiograph; and rapidly progressing disease.

50. What test can help physicians determine the needed biopsy sites for patients with suspected interstitial lung disease (ILD)?
Physicians use high-resolution computed tomography (HCRT) to help determine the best sites to biopsy in patients suspected of interstitial lung disease (ILD).

51. What is the primary objective of therapy in patients with interstitial lung disease (ILD)?
The most important tenet of therapy for patients with interstitial lung disease (ILD) is to remove the agent of injury, if possible. If the agent cannot be found and removed, suppressing inflammatory and cellular immune responses is the next priority.

52. What is the treatment for ILD dependent on?
The treatment method is dependent on the specific cause and symptoms.

53. Is coronavirus a potential cause of ILD?
Yes, ILD can occur secondary to coronavirus.

54. What is the most common drug administered for ILD?

55. Is lung scarring from ILD reversible?
No; once the damage has occurred, it is generally irreversible.

FAQs About Interstitial Lung Disease

How are Interstitial Lungs Diseases Diagnosed?

Interstitial lung diseases (ILDs) are diagnosed through a combination of clinical evaluation, imaging, and sometimes tissue sampling.

Key diagnostic tools include:

  • High-resolution computed tomography (HRCT) scans to obtain detailed images of the lungs.
  • Pulmonary function tests to assess lung capacity and function.
  • Blood tests to rule out conditions that mimic or are associated with ILD.
  • Bronchoscopy or surgical lung biopsy in certain cases to obtain lung tissue samples.
  • Detailed medical history and physical examination.

What is the Life Expectancy of a Person with Interstitial Lung Disease?

Life expectancy for someone with ILD varies significantly based on the specific type of ILD, its severity, the age of the patient, and other coexisting health conditions.

For instance, idiopathic pulmonary fibrosis (IPF), a form of ILD, generally has a prognosis of 3-5 years post-diagnosis.

However, many factors, including early diagnosis and appropriate treatment, can influence survival rates. It’s important for patients to consult with their healthcare provider for individual prognostic information.

What is the Most Common Cause of Interstitial Lung Disease?

The causes of ILD are varied, and in many cases, the exact cause remains unknown. However, some common causes or associations include:

  • Inhalation of environmental or occupational toxins (e.g., asbestos, silica)
  • Autoimmune diseases (e.g., rheumatoid arthritis, systemic lupus erythematosus)
  • Drug reactions (from medications like certain antibiotics, anti-inflammatory drugs, or heart medications)
  • Infections
  • Radiation therapy to the chest
  • Idiopathic conditions, where no clear cause is identified, are also prevalent, with idiopathic pulmonary fibrosis being one of the most common

Can You Recover from Interstitial Lung Disease?

The potential for recovery depends on the specific type of ILD, its cause, and the extent of lung damage. While some forms of ILD may stabilize or improve with treatment, others, especially those with significant fibrosis, may be irreversible.

Some ILDs, such as those due to drug reactions or certain infections, might improve once the cause is removed or treated.

Early diagnosis and intervention are crucial for a better outcome. Regular monitoring and appropriate management can also slow the progression of the disease in many cases.

Can You Reverse Interstitial Lung Disease?

While certain forms of ILD, particularly those with significant fibrosis, cannot be fully reversed, treatment can help manage symptoms, slow progression, or, in some instances, improve lung function.

The potential for reversibility often depends on the cause.

For example, ILDs due to drug reactions or certain infections might show improvement once the causative agent is removed or addressed. Nonetheless, early diagnosis and timely treatment are essential to optimize outcomes.

Can Interstitial Lung Disease Cause Dizziness?

Yes, interstitial lung disease can cause dizziness in some patients. The primary reason for this is decreased oxygen levels in the bloodstream due to impaired gas exchange in the lungs.

When the brain receives insufficient oxygen, it can result in symptoms like dizziness, lightheadedness, or even fainting.

Additionally, some medications used to treat ILD can also cause dizziness as a side effect.

How Rare is Interstitial Lung Disease?

The prevalence of ILD varies depending on the specific type and the population being studied. For example, idiopathic pulmonary fibrosis, one of the most common forms of ILD, affects approximately 10 per 100,000 people worldwide.

Other types of ILD, especially those associated with specific occupational exposures or rare autoimmune diseases, might be less common.

Overall, while ILDs are not as common as some other respiratory disorders, they represent a significant clinical challenge due to their potential to cause severe lung impairment.

Is Interstitial Lung Disease the Same as COPD?

No, interstitial lung disease and chronic obstructive pulmonary disease (COPD) are distinct entities, both in terms of causes and pathophysiology.

ILD primarily affects the interstitium of the lungs, leading to inflammation, fibrosis, or both. COPD, on the other hand, primarily affects the airways and air sacs, leading to airflow obstruction.

This obstruction is primarily due to emphysema (damage to the air sacs) and chronic bronchitis (inflammation and mucus production in the bronchial tubes).

While both conditions can result in respiratory symptoms and impairment, their management and prognoses can differ.

Is Interstitial Lung Disease Genetic?

While most cases of interstitial lung disease (ILD) are not directly inherited, there are familial forms of the disease, and genetics can play a role in susceptibility.

Some families have multiple members affected by ILD, suggesting a genetic predisposition.

Mutations in certain genes, such as TERT, TERC, and SFTPC, have been identified in familial forms of ILD, particularly idiopathic pulmonary fibrosis (IPF).

Additionally, certain genetic factors may increase an individual’s risk of developing ILD in the presence of environmental triggers or autoimmune conditions.

How Can I Prevent Interstitial Lung Disease?

Prevention strategies for ILD largely depend on its cause:

  • Occupational and environmental exposures: Avoid inhaling harmful substances like asbestos, silica, and certain organic dusts. Use protective equipment and follow safety guidelines if working in high-risk occupations.
  • Smoking: Cessation or avoidance of smoking can reduce the risk of developing some types of ILD and can prevent further lung damage in those already diagnosed.
  • Medications: Be aware of medications that can cause lung problems. If on such medications, undergo regular check-ups and notify a healthcare provider if respiratory symptoms develop.
  • Regular health check-ups: Especially if you have autoimmune diseases or other conditions associated with ILD, to catch and treat potential lung involvement early.

What are the Complications of Interstitial Lung Disease?

ILD can lead to various complications, including:

  • Respiratory failure: Due to severe impairment of gas exchange in the lungs.
  • Pulmonary hypertension: Elevated blood pressure in the arteries supplying the lungs, which can strain the heart.
  • Heart failure: Especially right-sided heart failure, resulting from increased pressure in the pulmonary circulation.
  • Chronic hypoxemia: Low blood oxygen levels, leading to symptoms like fatigue, dizziness, and blue discoloration of the lips or fingernails.
  • Pulmonary embolism: Blood clots traveling to the lungs.
  • Infections: Individuals with ILD may be more susceptible to lung infections.

Who is Most at Risk for Interstitial Lung Disease?

Those at higher risk for ILD include:

  • Older adults: Especially for idiopathic pulmonary fibrosis.
  • Smokers: Though smoking is more closely associated with COPD, it also increases the risk of certain ILDs.
  • People with autoimmune disorders: Such as rheumatoid arthritis or scleroderma.
  • Occupational exposure: Individuals exposed to asbestos, silica, coal dust, or certain other environmental agents.
  • Genetic predisposition: Individuals with a family history of ILD.
  • Certain medication and radiation therapy: Individuals who undergo chest radiation or take medications known to cause lung toxicity.

How Serious is Interstitial Lung Disease?

The severity of ILD varies depending on the subtype, its cause, and how advanced it is at the time of diagnosis.

Some types can be relatively mild and slow-progressing, while others, like idiopathic pulmonary fibrosis, can be rapidly progressive and life-threatening.

Regardless of the subtype, ILD can significantly impact an individual’s quality of life and overall lifespan, making early diagnosis and appropriate management critical.

Final Thoughts

Interstitial lung disease represents a challenging spectrum of pulmonary conditions characterized by inflammation or scarring of the lung tissue.

Its heterogeneous nature underscores the need for personalized care and a multidisciplinary approach to diagnosis and treatment.

Continued research and advancements in medical technology are vital in enhancing our understanding of ILD, offering better therapeutic options, and ultimately improving patient outcomes.

John Landry, BS, RRT

Written by:

John Landry, BS, RRT

John Landry is a registered respiratory therapist from Memphis, TN, and has a bachelor's degree in kinesiology. He enjoys using evidence-based research to help others breathe easier and live a healthier life.


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