OVERVIEW

What is interstitial lung disease?

Interstitial lung disease is a chronic condition caused by factors such as infections, medications, radiation, or genetics. Its main symptoms include coughing, shortness of breath, wheezing, and chest tightness, and it may also be accompanied by loss of appetite, weight loss, emaciation, and weakness.

Due to its numerous and often unclear causes, most types of interstitial lung disease cannot be completely cured. However, treatments such as corticosteroids, immunosuppressants, and bronchoalveolar lavage can help manage the condition. For example, idiopathic pulmonary fibrosis has an average survival period of only 2.8 to 3.6 years. Without early detection and treatment, the disease progresses rapidly, shortening the patient's lifespan.

The disease is not contagious, so isolation is unnecessary. However, as it progresses, the patient's quality of life can be significantly affected.

Is interstitial lung disease common?

Interstitial lung disease is not a common condition. Due to its many classifications, its incidence varies. A study in the U.S. found that its prevalence increased from 13.4 per 100,000 in 2005 to 18.2 per 100,000 in 2010. Early domestic surveys of hospitalized patients showed an increase from 0.11% in 1990 to 0.25% in 2004.

Are interstitial lung disease and pulmonary fibrosis the same?

Interstitial lung disease is a broad category of conditions involving the lung interstitium (including connective tissue, lymphatic vessels, nerve fibers, and blood vessels). Pulmonary fibrosis is a subset of this group, referring to diseases where interstitial inflammation and fibrosis are caused by factors such as viral infections, inhaled substances, or radiation.

What are the types of interstitial lung disease?

Interstitial lung disease mainly includes known-cause interstitial lung diseases, idiopathic interstitial pneumonia, granulomatous lung diseases, and other interstitial lung diseases. Idiopathic interstitial pneumonia is a group of conditions with unknown causes, and its classification has undergone multiple revisions without reaching consensus, with varying names across countries.

SYMPTOMS

What are the common manifestations of interstitial lung disease?

• Dry cough and exertional dyspnea: In the early stages of interstitial lung disease, symptoms are often subtle. As the disease progresses, patients may experience unexplained dry cough and shortness of breath during physical activity, which gradually worsens over time.

• Cyanosis: As the disease advances, cyanosis may appear on the lips, fingers, and toenails, presenting as a bluish-gray or dark purple discoloration. In severe cases, the color may become deep purple.

• Clubbing of fingers/toes: Approximately 50% of patients develop clubbing, characterized by thickening and widening of the distal fingers or toes. The nail bed becomes rounded, and the angle between the nail and the skin at the base exceeds 180°.

How does interstitial lung disease progress?

Interstitial lung disease often has an insidious onset, with variable progression rates. The disease may worsen continuously, and the speed of progression varies significantly depending on the type and individual differences. Some patients may die within weeks or months of diagnosis, while others may survive for up to 20 years.

What other diseases can interstitial lung disease cause?

The main complications of interstitial lung disease include respiratory failure and cor pulmonale. As the disease progresses, lung gas exchange function further declines, leading to inadequate oxygen intake, resulting in hypoxia, cyanosis, and clubbing. In later stages, increased pulmonary vascular resistance strains the heart, eventually leading to cor pulmonale.

CAUSES

What are the common causes of interstitial lung disease?

Interstitial lung disease, also known as diffuse parenchymal lung disease, has a wide range of causes, including those associated with a variety of diseases, exposures, and medications. Interstitial lung disease can also be idiopathic. Since treatment options and prognosis vary depending on the cause and type of interstitial lung disease, obtaining an accurate diagnosis is crucial. Possible causes of interstitial lung disease include:

• Various infectious diseases can cause interstitial shadows on a patient's chest X-ray, including fungal pneumonia (e.g., coccidioidomycosis, cryptococcosis, and Pneumocystis jirovecii pneumonia), atypical bacterial pneumonia, and viral pneumonia.

• The most common identifiable causes of interstitial lung disease are occupational and environmental exposures (particularly to inorganic or organic dust, such as asbestos) and drug-induced pulmonary toxicity (e.g., chronic beryllium disease).

• Most rheumatic diseases may be complicated by interstitial lung disease during their course, such as polymyositis/dermatomyositis, rheumatoid arthritis, systemic lupus erythematosus, systemic sclerosis (scleroderma), and mixed connective tissue disease.

• Idiopathic causes of interstitial lung disease include sarcoidosis, cryptogenic organizing pneumonia, acute and chronic eosinophilic pneumonia, and idiopathic interstitial pneumonia.

Who is most likely to develop interstitial lung disease?

Interstitial lung disease is common among individuals prone to exposure to related triggers, such as miners or those exposed to asbestos, silica dust, sulfur dioxide, heavy metal vapors, or toxic gases at work. Another group includes cancer patients who experience side effects from radiotherapy, chemotherapy, or molecular-targeted drugs.

Immunocompromised patients, such as those with HIV or organ transplants, are also susceptible to viral or bacterial infections leading to interstitial pneumonia, which may progress to pulmonary fibrosis. Others, such as those taking long-term antiarrhythmic drugs like amiodarone, drug abusers, or individuals with paraquat poisoning, may also develop interstitial lung disease.

Is interstitial lung disease contagious?

Interstitial lung disease is not contagious.

Is interstitial lung disease hereditary?

Interstitial lung disease is not hereditary.

DIAGNOSIS

How is interstitial lung disease diagnosed?

When diagnosing interstitial lung disease, doctors primarily rely on chest X-rays, lung CT scans, pulmonary function tests, and bronchoscopy to determine the subtype of the disease.

What tests are needed for interstitial lung disease?

Generally, a chest X-ray or lung CT scan and pulmonary function tests are required.

• Chest X-ray or lung CT: Mainly used to detect interstitial changes in the lungs, such as ground-glass opacities, as well as nodular, patchy, or reticular shadows.

• Pulmonary function tests: Primarily used to assess changes in lung ventilation and gas exchange. Patients with pulmonary fibrosis typically exhibit restrictive ventilatory dysfunction and reduced diffusion capacity.

What should be noted during pulmonary function tests for interstitial lung disease?

During pulmonary function tests, it is important to cooperate with the medical staff. If dizziness or coughing occurs, inform the doctor and take a short break before resuming the test.

Which diseases can interstitial lung disease be confused with, and how to differentiate them?

Due to its subtle early symptoms and reliance on imaging for diagnosis, interstitial lung disease may be confused with conditions like common pneumonia, pulmonary embolism, or alveolar cell carcinoma. Doctors differentiate these conditions through blood tests, lung CT scans, tumor markers, and bronchoalveolar lavage or biopsy via electronic bronchoscopy.

TREATMENT

Which department should I visit for interstitial lung disease?

If you suspect or have been diagnosed with interstitial lung disease, you should go to the respiratory department. If there is no specialized respiratory department, you should visit the internal medicine department.

Can interstitial lung disease heal on its own?

Interstitial lung disease cannot heal on its own. Early diagnosis and treatment are necessary to prolong survival, otherwise the progression of the disease may accelerate.

How is interstitial lung disease treated?

The main treatment methods for interstitial lung disease include medication and surgery. Due to the numerous causes and complex mechanisms of interstitial lung disease, most cases lack effective treatments. Drug therapy primarily involves glucocorticoids combined with immunosuppressants. Recent findings suggest that some anti-tumor drugs may also have therapeutic effects on interstitial lung disease.

For patients in the middle or late stages, lung transplantation may be an option. Pulmonary rehabilitation is also currently recommended as one of the treatment options for interstitial lung disease, though its effects are limited and should be combined with medication to extend survival. Many so-called "miracle cures" advertised on TV or in newspapers are often scams, possibly containing glucocorticoids that may temporarily improve symptoms but increase the risk of infection and accelerate disease progression.

Does interstitial lung disease require hospitalization?

If interstitial lung disease is suspected, prompt medical attention is necessary. Hospitalization may be required for further tests to determine the subtype. Hospitalization is also necessary if complications such as infection, respiratory failure, or pulmonary heart disease occur.

What are the common side effects of medications for interstitial lung disease?

One of the common medications for interstitial lung disease is glucocorticoids. Long-term oral use of glucocorticoids may cause side effects such as:

• Disorders in water, salt, sugar, protein, and fat metabolism: Symptoms include central obesity (round face, broad shoulders), acne, excessive hair growth, high blood pressure, edema, hyperlipidemia, and hyperglycemia.

• Long-term use may also lead to adrenal cortex dysfunction or even atrophy, resulting in symptoms like amenorrhea, muscle wasting, weakness, osteoporosis, femoral head necrosis, and psychiatric symptoms.

However, patients should strictly follow the treatment plan prescribed by their doctor and must not reduce the dosage or stop the medication without medical advice.

What are the common risks of surgical treatment for interstitial lung disease?

The surgical treatment for interstitial lung disease is lung transplantation, which is a major and highly complex procedure with significant costs. Common risks include post-operative infections, graft dysfunction due to ischemia, and acute or chronic rejection.

How long is the recovery period after surgical treatment for interstitial lung disease?

After lung transplantation, patients with interstitial lung disease need to take anti-rejection medications, making infection prevention crucial:

• Avoid crowded places after surgery.

• Limit visitors at home for the first two months post-surgery, and avoid lifting objects heavier than 5 kg for the first six weeks.

• Avoid keeping pets and stay away from dusty or strongly irritating environments.

• Most patients can stop using oxygen within two weeks, walk 1.5 kilometers within 2–4 weeks, and return to work after three months. Follow-up visits are required every two months.

With proper post-operative care, adherence to medication, and regular check-ups, most patients can return to normal life within six months.

Can interstitial lung disease be cured?

Currently, there is no medication that can cure interstitial lung disease. After diagnosis and classification, drug therapy can be used to slow disease progression, and lung transplantation may be considered in advanced stages.

DIET & LIFESTYLE

What should patients with interstitial lung disease pay attention to in their diet?

• Reduce salt intake and avoid overly salty foods such as pickles, kimchi, cured meats, etc.;

• Reduce cholesterol and fat intake. Consume meat and dairy products in moderation and avoid high-fat foods;

• Reduce sugar intake. Since glucocorticoid medications can increase blood sugar levels, minimize the consumption of sugary foods and desserts;

• Limit alcohol intake. It is best to avoid alcohol altogether, as it may cause adverse reactions with medications.

What should patients with interstitial lung disease pay attention to in daily life?

Engage in appropriate exercise, such as moderate-intensity outdoor aerobic activities. Consult a pulmonary rehabilitation specialist to develop a tailored rehabilitation plan, which can aid in disease management. Avoid excessive stress and ensure adequate sleep daily.

Does interstitial lung disease affect fertility?

Interstitial lung disease does not impact fertility, but patients should avoid overexertion.

Can patients with interstitial lung disease travel by plane, engage in strenuous exercise, or visit high-altitude areas?

Due to impaired lung ventilation and gas exchange, patients should avoid strenuous activities and high-altitude travel. Moderate outdoor exercise is acceptable, preferably under the guidance of a pulmonary rehabilitation specialist.

How should patients with interstitial lung disease be cared for?

If a family member has interstitial lung disease, minimize their exposure to pathogens such as dust and irritating chemical fumes. If the condition is caused by medications or treatments, consult a doctor promptly to adjust the treatment plan if necessary.

At home, avoid strenuous activities and heavy physical labor. Maintain a balanced diet and regular sleep schedule. Adjust clothing according to seasonal and weather changes to prevent bacterial or viral infections that may worsen the condition.

PREVENTION

Can interstitial lung disease be prevented? How to prevent it?

Some interstitial lung diseases can be prevented:

• Workers exposed to pathogens should take protective measures at work or consider changing jobs;

• People with weakened immune systems should avoid crowded areas as much as possible;

• For patients who cannot avoid exposure, seek medical attention promptly if unexplained dry cough or shortness of breath after activity occurs.

• However, the causes of most interstitial lung diseases are unclear, or even if the cause is known, prevention may not be possible, such as pulmonary complications from other diseases (rheumatic immune diseases, tumors) or side effects of treatments (radiotherapy, chemotherapy). Regular check-ups and timely treatment when interstitial lung disease appears can help slow its progression.

How to prevent recurrence of interstitial lung disease?

Interstitial lung disease is progressive, and current treatments can only slow its progression. However, infections may occur during treatment. To prevent recurrent infections, avoid crowded places, dress appropriately for temperature changes, wear masks in severe outdoor air pollution, engage in moderate physical exercise, maintain a regular routine, and eat a healthy diet—all of which can help prevent secondary infections.

How can patients with interstitial lung disease prevent other diseases?

• Interstitial lung disease is progressive, and its main complications include respiratory failure and pulmonary heart disease. To prevent respiratory failure, regularly check blood oxygen levels. If blood oxygen is low, adopt a home oxygen therapy plan to avoid hypoxia, which can also reduce symptoms like cyanosis and clubbing of fingers or toes.

• Pulmonary heart disease results from increased pulmonary circulation pressure and cardiac load. After being diagnosed with interstitial lung disease, patients should undergo regular echocardiograms and pulmonary artery pressure assessments. If pulmonary hypertension is detected, medications to lower pulmonary artery pressure or improve heart function can be administered promptly.