What causes of interstitial lung disease?

What is interstitial lung disease?

Interstitial lung disease (ILD) refers to a group of over 200 lung conditions characterized by inflammation or scarring (fibrosis) of the interstitium – the tissue and space around the air sacs (alveoli) in the lungs. This interferes with normal breathing by affecting gas exchange at the thin blood vessels (capillaries). Many ILD have no definite cause while others have known triggers. The severity varies depending on the extent and type of lung tissue affected.

What causes interstitial lung diseases?

Some potential causes of ILD include:

• Connective tissue diseases: Rheumatoid arthritis, scleroderma, lupus and others may cause ILD in up to 30% cases.
• Environmental exposures: Toxic gases, metal dusts, organic dusts, radiation therapy, smoking, pollution over long periods.
• Medications: Amiodarone, bleomycin, nitrofurantoin, methotrexate, proton pump inhibitors linked to rare cases.
• Genetic syndromes: Tuberous sclerosis, Birt-Hogg-Dubé, Hermansky-Pudlak syndrome predispose to ILD.
• Pulmonary fibrosis: Idiopathic pulmonary fibrosis has no identifiable reason for scarring.
• Sarcoidosis: Noncaseating granulomas in lungs of unclear cause.
• Hypersensitivity pneumonitis: “Farmer’s lung” caused by recurrent small particle exposures.

What are the symptoms of interstitial lung diseases?

Early symptoms are subtle and non-specific but may include:

• Dry cough that worsens over time
• Shortness of breath with activity requiring breathing efforts
• Fatigue, tiredness exacerbated by exertion
• Crackles or velcro-like sounds while breathing
• Finger clubbing in advanced disease
• Low-grade fever in infections or other underlying causes

Gradual worsening leads to cyanosis, respiratory failure needing oxygen support. Timely diagnosis improves outcomes.

How are interstitial lung diseases diagnosed?

A combination of tests are used to confirm and excludes other respiratory conditions:

• Complete medical history and examination focusing on symptoms and risk factors.
• Spirometry: Measures breathing capacity via forced expiratory flows. Restrictive lung disease pattern seen in ILD.
• Chest X-rays: May show infiltrates, scarring, honeycombing in advanced cases.
• CT scan: High-resolution imaging necessary for accurate identification of patterns seen in specific ILD types.
• Lung biopsy: Tissue sample observed under microscope to differentiate ILD. Bronchoscopy guided or surgical options.
• Blood tests: Rule out infection, assess inflammation. Elevated ANA indicates autoimmunity.
• Pulmonary function tests: Lung volume measurement aids severity assessment.

Other tests as needed based on differentials like chest MRI, echocardiogram, sleep study, etc.

Early accurate diagnosis key for optimal management selection based on the etiology, inflammatory activity, and fibrotic burden determined. A multidisciplinary team guides care.

How are interstitial lung diseases treated?

Treatment aims at slowing disease progression, managing symptoms, and improving quality of life:

• Supplemental oxygen: For hypoxemia to avoid complications.
• Corticosteroids: Anti-inflammatory drugs may benefit specific ILD types depending severity.
• Immunosuppressants: Drugs like azathioprine, mycophenolate mofetil, cyclophosphamide for autoimmune ILD.
• Antifibrotics: Nintedanib and pirfenidone approved for IPF to reduce scarring.
• Lung transplantation: In select refractory ILD cases that heavily impact survival.
• Pulmonary rehabilitation: Respiratory muscle training and breathing techniques.
• Managing infections, oxygen desaturations.
• Palliative care: For advanced disease symptom relief and care planning.
• Lifestyle changes: Avoiding aggravating triggers, flu vaccination, nutrition.

With careful monitoring and treatments tailored to individual diagnosis, ILD lives can be significantly improved.

In summary, interstitial lung diseases arise due to numerous causes leading to lung interstitium scarring or inflammation and fibrosis. Early diagnosis aided by thorough evaluation and tests helps guide customized treatment approaches for optimal management of the chronic conditions. Further research enhances understanding and management outcomes of this diverse group of lung disorders.