Idiopathic pulmonary fibrosis

What it is, symptoms and effects

From: MedlinePlus Genetics, National Library of Medicine

Idiopathic pulmonary fibrosis is a chronic, progressive lung disease. This condition causes scar tissue (fibrosis) to build up in the lungs, which makes the lungs unable to transport oxygen into the bloodstream effectively. The disease usually affects people between the ages of 50 and 70. Idiopathic pulmonary fibrosis belongs to a group of conditions called interstitial lung diseases (also known as ILD), which describes lung diseases that involve inflammation or scarring in the lung.

The most common signs and symptoms of idiopathic pulmonary fibrosis are shortness of breath and a persistent dry, hacking cough. Many affected individuals also experience a loss of appetite and gradual weight loss. Some people with idiopathic pulmonary fibrosis develop widened and rounded tips of the fingers and toes (clubbing) resulting from a shortage of oxygen. These features are relatively nonspecific; not everyone with these health problems has idiopathic pulmonary fibrosis. Other respiratory diseases, some of which are less serious, can cause similar signs and symptoms.

In people with idiopathic pulmonary fibrosis, scarring of the lungs increases over time until the lungs can no longer provide enough oxygen to the body's organs and tissues. Some people with idiopathic pulmonary fibrosis develop other serious lung conditions, including lung cancer, blood clots in the lungs (pulmonary emboli), pneumonia, or high blood pressure in the blood vessels that supply the lungs (pulmonary hypertension). Most affected individuals survive 3 to 5 years after their diagnosis. However, the course of the disease is highly variable; some affected people become seriously ill within a few months, while others may live with the disease for a decade or longer.

In most cases, idiopathic pulmonary fibrosis occurs in only one person in a family. These cases are described as sporadic. However, a small percentage of people with this disease have at least one other affected family member. When idiopathic pulmonary fibrosis occurs in multiple members of the same family, it is known as familial pulmonary fibrosis.

Causes and biological mechanisms

From: MedlinePlus Genetics, National Library of Medicine

The cause of idiopathic pulmonary fibrosis is unknown. The fibrosis that builds up in the lungs is thought to develop as a result of abnormal tissue repair following tissue damage. This abnormal repair response probably results from a combination of genetic and environmental factors. It is likely that genetic changes increase a person's risk of developing idiopathic pulmonary fibrosis, and then exposure to certain environmental factors triggers the disease.

Changes in several genes have been suggested as risk factors for idiopathic pulmonary fibrosis, while it is likely that other genetic influences have yet to be discovered. Most of the known genetic changes account for only a small proportion of cases of idiopathic pulmonary fibrosis. However, mutations in genes known as TERC and TERT have been found in about 15 percent of all cases of familial pulmonary fibrosis and a smaller percentage of cases of sporadic idiopathic pulmonary fibrosis. The TERC and TERT genes provide instructions for making components of an enzyme called telomerase, which maintains structures at the ends of chromosomes known as telomeres. A decrease in telomerase function allows telomeres to become abnormally short as cells divide. The shortened telomeres likely trigger lung cells to stop dividing or to die prematurely. In people with idiopathic pulmonary fibrosis, shorter telomeres are associated with a more severe disease and a quicker decline in lung function. Additional research is needed to confirm how shortened telomeres contribute to the progressive scarring and lung damage characteristic of idiopathic pulmonary fibrosis.

Researchers have also examined environmental risk factors that could contribute to idiopathic pulmonary fibrosis. These factors include exposure to wood or metal dust, viral infections, certain medications, and cigarette smoking. Some research suggests that gastroesophageal reflux disease (GERD) may also be a risk factor for idiopathic pulmonary fibrosis; affected individuals may breathe in (aspirate) stomach contents, which over time could damage the lungs.

Inheritance and family implications

From: MedlinePlus Genetics, National Library of Medicine

Most cases of idiopathic pulmonary fibrosis are sporadic; they occur in people with no history of the disorder in their family.

Familial pulmonary fibrosis appears to have an autosomal dominant pattern of inheritance. Autosomal dominant inheritance means one copy of an altered gene in each cell is sufficient to cause the disorder. However, some people who inherit the altered gene never develop features of familial pulmonary fibrosis. (This situation is known as reduced penetrance.) It is unclear why some people with a mutated gene develop the disease and other people with the mutated gene do not.

How common is it?

From: MedlinePlus Genetics, National Library of Medicine

Idiopathic pulmonary fibrosis has an estimated prevalence of 13 to 20 per 100,000 people worldwide. About 100,000 people are affected in the United States, and 30,000 to 40,000 new cases are diagnosed each year.

Familial pulmonary fibrosis is less common than the sporadic form of the disease. Only a small percentage of cases of idiopathic pulmonary fibrosis appear to run in families.

Reported clinical features and what the terms mean

The following findings are associated with this condition in Orphanet. They are not a checklist for diagnosing yourself, and they do not all occur in every affected person. Some are examination, imaging or laboratory findings that cannot be recognised at home.

The frequency labels describe how often a finding was reported among people with the condition in the source. They do not give the chance that a person with that symptom has the condition. Definitions below reproduce HPO terminology; they explain the term, not the likely severity in an individual.

Abnormal pulmonary interstitial morphology · Very frequent (99-80%)

Abnormality of the lung parenchyma extending to the pulmonary interstitium and leading to diffuse pulmonary fibrosis.

Acrocyanosis · Frequent (79-30%)

Bluish discoloration of the skin of the hands or feet.

Bronchiectasis · Frequent (79-30%)

Persistent abnormal dilatation of the bronchi owing to localized and irreversible destruction and widening of the large airways.

Clubbing of fingers · Frequent (79-30%)

Terminal broadening of the fingers (distal phalanges of the fingers).

Cough · Frequent (79-30%)

A sudden, audible expulsion of air from the lungs through a partially closed glottis, preceded by inhalation.

Crackles · Frequent (79-30%)

Crackles are discontinuous, explosive, and nonmusical adventitious lung sounds normally heard in inspiration and sometimes during expiration. Crackles are usually classified as fine and coarse crackles based on their duration, loudness, pitch, timing in the respiratory cycle, and relationship to coughing and changing body position.

Decreased DLCO · Frequent (79-30%)

Reduced ability of the lungs to transfer gas from inspired air to the bloodstream as measured by the diffusing capacity of the lungs for carbon monoxide (DLCO) test.

Exertional dyspnea · Frequent (79-30%)

Perceived difficulty to breathe that occurs with exercise or exertion and improves with rest.

Other findings in the same source

From: Orphanet

Additional reported features include Fatigue (Frequent (79-30%)); Gastroesophageal reflux (Frequent (79-30%)); Ground-glass opacification on pulmonary HRCT (Frequent (79-30%)); Honeycomb lung (Frequent (79-30%)); Pulmonary fibrosis (Frequent (79-30%)); Reduced forced vital capacity (Frequent (79-30%)); Reticular pattern on pulmonary HRCT (Frequent (79-30%)); Subpleural honeycombing (Frequent (79-30%)); Usual interstitial pneumonia (Frequent (79-30%)); Exercise intolerance (Occasional (29-5%)). This is a selected summary, not a complete description of the condition.

Which doctor should you see?

The suggested department for discussing Idiopathic pulmonary fibrosis is Pulmonology, with a pulmonologist / chest physician as the relevant type of clinician. General physician / Family Medicine; paediatrician for children. Referral depends on symptoms.

Additional services that may be relevant, depending on the findings, include: Clinical Genetics.

This is an editorial referral starting point. The appropriate clinic depends on the person’s age, symptoms, previous diagnosis and local services. The first clinician can decide whether another specialty or a team is needed; a department label does not confirm the diagnosis.

How to prepare for an assessment

Bring a short timeline of the main symptoms: when they first appeared, whether they are constant or episodic, what seems to change them, and how they affect daily activities. Include previous reports, discharge summaries, current medicines and supplements, allergies, and any relevant family history. A dated record is more useful than trying to match every feature in an online article.

Ask the clinician what is already established and what remains uncertain. If a test is suggested, ask what question it answers, what its limitations are and how the result would change the next step. The information here is not an instruction to arrange every possible test. In children, bring growth, developmental and school information if it is relevant to the concern.

• What is the likely explanation for the breathing symptoms?
• Would a breathing test or another investigation change management?
• If symptoms worsen, what written action plan should be followed?

Treatment discussions and follow-up

The material gathered for this draft does not provide a complete condition-specific treatment pathway for Idiopathic pulmonary fibrosis. That gap does not mean that treatment is unavailable. A clinician needs to establish the diagnosis and review current guidance before recommending medicines, procedures, rehabilitation or other support.

Before leaving the appointment, clarify the next review date, who will communicate results, and whom to contact if the situation changes. Discuss difficulties with sleep, work, school, mobility, eating or emotional wellbeing when these are relevant. Practical support may require coordination between the treating clinician and other services.

The collected references do not establish a complete prevention or long-term outlook section for this entry. Missing information should not be interpreted as proof that prevention is impossible or that a particular outcome is inevitable. Ask what is known for the exact subtype, stage and personal circumstances, and which uncertainties remain.

When to seek emergency help

Severe breathing difficulty, collapse, new stroke-like symptoms, a seizure that is prolonged or repeated without recovery, uncontrolled major bleeding, or an immediate risk of self-harm require emergency help. In India, call 112 or reach the nearest emergency department. This is a general, non-exhaustive warning list; it is not a condition-specific triage tool.