Lung Fibrosis — Symptoms, Causes & Treatment | MyMedicPlus

Pulmonary fibrosis is the progressive scarring and thickening of lung tissue, reducing the ability to breathe effectively. Idiopathic pulmonary fibrosis (IPF) is the most common and severe form with unknown cause. Over 5 million people are affected globally. Median survival after diagnosis is 3-5 years without treatment, though antifibrotics improve outcomes. Pulmonary fibrosis refers to progressive scarring (fibrosis) of lung tissue, reducing lung compliance and gas exchange capacity. The most common form, idiopathic pulmonary fibrosis (IPF), affects approximately 3 per 10,000 adults, predominantly men over age 60 with a history of smoking. Other forms include hypersensitivity pneumonitis (from organic dust or bird antigen exposure), connective tissue disease-associated interstitial lung disease (ILD in rheumatoid arthritis, systemic sclerosis, myositis), and drug-induced fibrosis (amiodarone, methotrexate, nitrofurantoin). Prognosis varies significantly by type — IPF has a median survival of 3-5 years from diagnosis, while connective tissue disease-associated ILD may be more stable.

IPF has no identified cause but risk factors include age over 60, male sex, cigarette smoking, gastroesophageal reflux, and genetic predisposition (MUC5B, TERT mutations). Secondary causes include rheumatoid arthritis, systemic sclerosis, hypersensitivity pneumonitis (bird fancier's lung, farmer's lung), radiation, and drug toxicity (amiodarone, methotrexate, bleomycin). IPF pathophysiology involves repeated subclinical epithelial injury followed by aberrant wound healing — activating TGF-beta signalling that drives fibroblast proliferation and excessive extracellular matrix deposition replacing normal alveolar architecture with honeycombing. Established risk factors for IPF include cigarette smoking (present in approximately 75% of IPF patients), occupational dust exposures (silica, wood dust, metal dust), viral infections (EBV, CMV, HHV-7, 8), and microaspiration from subclinical GERD. Genetic risk factors include telomerase gene mutations (TERT, TERC) in familial IPF, and MUC5B promoter polymorphism (rs35705950) which increases IPF risk 5-fold.

Progressive exertional dyspnea, persistent dry cough, fatigue, weight loss, and finger clubbing are hallmark features. Bibasal inspiratory crackles (Velcro-like) on auscultation are characteristic. Cyanosis and cor pulmonale develop in advanced disease. Acute exacerbations with rapid deterioration can be life-threatening. The hallmark symptom is progressive exertional dyspnoea — initially on strenuous activity, then ordinary activities, then rest as the disease advances. Persistent dry cough (non-productive, often refractory to antitussives) is the second most common symptom, causing significant distress. Fine inspiratory crackles ('Velcro crackles') at the lung bases on auscultation are characteristic of IPF. Clubbing of the fingers and toes occurs in 50% of IPF patients. Cyanosis and respiratory failure with hypoxaemia develop in advanced disease. Constitutional symptoms — fatigue, weight loss — are present in some cases.

High-resolution CT (HRCT) chest showing basal-predominant honeycombing with or without traction bronchiectasis is the key diagnostic feature (UIP pattern). Pulmonary function tests reveal restrictive pattern with reduced DLCO. Surgical lung biopsy confirms diagnosis when HRCT is atypical. Multidisciplinary team discussion with pulmonologist, radiologist, and pathologist is standard. High-resolution CT (HRCT) of the chest is the essential imaging investigation — in IPF, it shows a usual interstitial pneumonia (UIP) pattern: bilateral, basal-predominant, subpleural honeycombing with or without traction bronchiectasis; peribronchovascular distribution suggests alternative diagnosis. Pulmonary function tests (PFTs) show a restrictive pattern: reduced FVC (below 80% predicted), reduced DLCO (below 70% predicted), and preserved FEV1/FVC ratio. Six-minute walk test (6MWT) quantifies functional impairment and desaturation. Bronchoalveolar lavage (BAL) and surgical lung biopsy are reserved for atypical presentations where HRCT pattern is non-diagnostic. Serological screening for connective tissue disease (ANA, anti-CCP, anti-dsDNA, myositis panel, RF) excludes secondary ILD.

Antifibrotic agents nintedanib (tyrosine kinase inhibitor) and pirfenidone slow the rate of FVC decline by approximately 50% and reduce acute exacerbation risk. Treat comorbidities: GERD with PPIs, pulmonary hypertension with approved agents. Supplemental oxygen for hypoxemia. Pulmonary rehabilitation improves quality of life. Lung transplantation is the only curative option for eligible patients. Antifibrotic therapy for IPF: pirfenidone (PLEX/Esbriet — inhibits TGF-beta and multiple fibrotic pathways; dose 2403 mg/day in three divided doses) and nintedanib (Ofev — VEGFR/PDGFR/FGFR tyrosine kinase inhibitor; 150 mg twice daily) both reduce FVC decline rate by approximately 50% over 52 weeks and are approved for mild-moderate IPF (FVC above 50%). They are not cures but slow disease progression. Lung transplantation is the only curative option for eligible patients — improving median survival from 3 to 5-6 years; bilateral sequential transplantation is preferred over single-lung transplant. Supplemental oxygen for patients with resting hypoxaemia (PaO2 below 8 kPa) or significant exertional desaturation improves quality of life and survival. Pulmonary rehabilitation improves exercise capacity and dyspnoea symptoms.

See a GP or respiratory specialist promptly for: progressively worsening breathlessness on exertion, persistent dry cough, or new finger clubbing — these are the cardinal features of interstitial lung disease. Any new breathlessness in a person over 50 (especially with a history of smoking, occupational dust exposure, connective tissue disease, or prior drug exposure) warrants urgent investigation with HRCT chest and pulmonary function tests. Seek emergency care for: sudden severe worsening of breathlessness or cyanosis (acute exacerbation of IPF is a life-threatening emergency with mortality of 40-50% — requires urgent admission with high-flow oxygen, non-invasive ventilation, and IV corticosteroids). An established IPF diagnosis with previously stable disease that suddenly worsens acutely requires emergency hospital admission. All patients with confirmed ILD should be managed by a multidisciplinary ILD team at a specialist centre — including respiratory medicine, rheumatology (for connective tissue disease-associated ILD), physiotherapy, palliative care input, and transplant assessment where appropriate.

Pulmonary fibrosis generates progressive life-threatening complications. Respiratory failure — the primary cause of death — develops as progressive fibrosis reduces functional alveolar surface area causing hypoxaemia (PaO2 below 8 kPa at rest), requiring supplemental oxygen initially on exertion then continuously. Acute exacerbations — sudden unexplained accelerated worsening with new bilateral ground-glass opacities on HRCT — carry 70-90% in-hospital mortality. Pulmonary hypertension complicates 30-50% of patients with advanced fibrosis — right ventricular pressure overload causes cor pulmonale with right heart failure, peripheral oedema, and ascites. Lung cancer risk is increased 4-8 fold in pulmonary fibrosis patients. Secondary polycythaemia from chronic hypoxaemia increases thrombosis risk significantly. Recurrent respiratory infections — including pneumonia and mycobacterial infections — occur in fibrotic lungs with impaired mucociliary clearance and bronchiectasis. Depression and severe anxiety affect 30-50% of patients, and progressive disability causes loss of independence and social isolation. Pneumothorax from rupture of subpleural fibrotic cysts or honeycomb lesions requires chest drain insertion.

Smoking cessation is the most important modifiable risk factor. Treat GERD aggressively to prevent microaspiration-induced injury. Avoid known fibrogenic agents including avian antigens, mold, and occupational dusts. Annual influenza and pneumococcal vaccination reduces exacerbation risk. Enroll in a specialized ILD center for optimal multidisciplinary management. Prevention focuses on eliminating identifiable trigger exposures. Smoking cessation is the single most important preventive measure for IPF — smoking is present in 75% of cases and continuation accelerates fibrotic progression. Occupational exposure control: adequate respiratory protection (P3 masks, engineering controls) for workers exposed to silica, asbestos, metal dust, and organic dust; occupational health surveillance with periodic spirometry. GERD management with proton pump inhibitors may reduce microaspiration-driven epithelial injury — PPIs are recommended in all IPF patients regardless of symptomatic reflux. Hypersensitivity pneumonitis prevention requires complete and permanent removal from the causative antigen (bird keeping, mould exposure, workplace organic dusts) — continued exposure after diagnosis causes rapid fibrotic progression.