What is pulmonary fibrosis and what causes it?

What is Pulmonary Fibrosis?

Pulmonary fibrosis is a lung disease where your lungs become scarred and stiff, making it progressively harder to breathe. 1, 2 Think of it like your lungs developing thick scar tissue that prevents them from expanding and contracting normally, similar to how a rubber band loses its stretch when it gets old and damaged. 1

How Your Lungs Are Affected

• Your lungs normally have tiny air sacs (like microscopic balloons) that fill with air when you breathe 1
• In pulmonary fibrosis, scar tissue builds up around these air sacs, making the lung tissue thick and stiff 1, 3
• This scarring prevents oxygen from passing easily into your bloodstream, causing shortness of breath, especially during physical activity 2, 4
• The disease is progressive, meaning it typically gets worse over time 1, 2

What Causes Pulmonary Fibrosis?

The causes fall into several categories:

Unknown Causes (Idiopathic)

• In many cases, doctors cannot identify a specific cause—this is called "idiopathic pulmonary fibrosis" or IPF 1, 2
• IPF primarily affects people over age 60, with most patients in their 60s and 70s 1, 2
• Men are affected more often than women 1, 2

Environmental and Occupational Exposures

• Cigarette smoking is a significant risk factor, increasing your risk 1.6 to 2.9 times 1
• Metal dust and wood dust exposure (especially steel, brass, lead, and pine wood) from years of workplace exposure 1
• Asbestos, silica, and other mineral dusts from construction, mining, or manufacturing work 1, 5
• Chronic exposure to mold, bird droppings, or agricultural dust (called hypersensitivity pneumonitis) 1

Medications

• Certain chemotherapy drugs like bleomycin and cyclophosphamide 5
• Heart medications like amiodarone 5
• Antibiotics like nitrofurantoin 5
• Other drugs including gold, penicillamine, and procainamide 5

Medical Conditions

• Autoimmune diseases such as rheumatoid arthritis, systemic sclerosis (scleroderma), and lupus 1, 5
• Chronic acid reflux (gastroesophageal reflux) with repeated aspiration of stomach contents into the lungs 1, 2

Infections

• Possible association with viral infections including Epstein-Barr virus, hepatitis C, and cytomegalovirus, though this remains uncertain 1, 2

Genetic Factors

• About 30% of patients have genetic factors that increase their risk 2
• Some families have multiple members affected (familial pulmonary fibrosis) 1
• Genetic mutations affecting telomeres (the protective caps on chromosomes) are associated with premature aging of lung cells 1

Common Symptoms

• Progressive shortness of breath, especially with physical activity 2, 4
• Persistent dry cough that doesn't respond to typical cough medicines 2
• Crackling sounds in the lungs (like Velcro being pulled apart) that doctors hear with a stethoscope 2
• Clubbing of fingertips (fingertips become rounded and enlarged) in less than half of patients 2, 3
• Fatigue and general weakness as the disease progresses 4

Prognosis

• Without treatment, the median survival is 2-4 years after diagnosis 2, 4, 3
• The disease is progressive and currently cannot be cured, though medications can slow its progression 2, 4
• Lung transplantation is the only treatment that can improve survival for eligible patients 2