In idiopathic pulmonary fibrosis, the lungs develop progressive scarring for unknown reasons. There seems to be a genetic component because some families have more than one person affected by the disorder. Specific gene mutations have been identified in some people with idiopathic pulmonary fibrosis.
Symptoms depend on the extent of the lung damage, the rate at which the disease progresses, and whether complications, such as lung infections and right-sided heart failure (cor pulmonale) develop.
The main symptoms start insidiously as shortness of breath during exertion, cough, and diminished stamina. In most people, symptoms worsen over a period ranging from about 6 months to several years.
As the disease progresses, the level of oxygen in the blood decreases, and the skin may take on a bluish tinge (called cyanosis) and the ends of the fingers may become thick or club-shaped (see figure Recognizing Finger Clubbing). Strain on the heart may cause the right ventricle to enlarge, eventually resulting in right-sided heart failure. Through a stethoscope, doctors often hear crackling sounds in the lungs.
A chest x-ray may show lung damage, mostly in the lower parts of both lungs. Computed tomography (CT) typically shows the damage and thick scarring in more detail. Pulmonary function tests show that the amount of air the lungs can hold is below normal. Analysis of a blood sample (see Arterial Blood Gas Analysis) or use of an oximeter shows a low level of oxygen during minimal exercise (walking at a normal pace) and, as the disease progresses, even when the person is resting.
To confirm the diagnosis, doctors may do a lung biopsy with use of a thoracoscope.
Blood tests cannot confirm the diagnosis but are done as part of the search for other disorders that may cause a similar pattern of inflammation and scarring. For example, doctors do blood tests to screen for certain autoimmune disorders.
Most people continue to get worse. On average, people live about 3 to 5 years after diagnosis. Some people survive for more than 5 years after diagnosis. A few die within several months.
Pirfenidone and nintedanib appear to slow the decline in lung function. Other drug treatments are being studied in clinical trials.
Other treatments are aimed at relieving symptoms:
Pulmonary rehabilitation for improving ability to carry out activities of daily life
Oxygen therapy for low blood oxygen levels
Antibiotics for infection
Drugs for the heart failure that is caused by cor pulmonale
Lung transplantation (in some cases with a single lung) has been successful in some people with severe idiopathic pulmonary fibrosis.