Idiopathic pulmonary fibrosis is a serious disease where the alveoli (the tiny air sacs of the lungs) and the lung tissue next to the alveoli become damaged and scarred. The main symptom is shortness of breath that gradually gets worse. The exact cause is not known. Treatments include steroids, and other medicines, and increasingly lung transplantation may be offered.
It is useful to understand what the following words mean:
Idiopathic pulmonary fibrosis used to be called cryptogenic fibrosing alveolitis. The exact cause is not known (hence the term idiopathic). It was thought that inflammation within the alveoli played a big role in the development of idiopathic pulmonary fibrosis and that this inflammation led to scarring and fibrosis. This led to the name cryptogenic fibrosing alveolitis. However, treatments that help to reduce inflammation are not always effective. Therefore, the role of inflammation has recently been brought into question.
The current thinking is that somehow the cells that line the alveoli are damaged in some way. The cells then try to heal themselves. But, this healing process becomes out of control, causing thickening and damage to the walls of the alveoli, and fibrosis (scarring) of the alveoli and lung tissue. The thickening and scarring reduces the amount of oxygen that can pass into the blood vessels from affected alveoli. Therefore, as the disease progresses, less oxygen than normal is passed into the body when you breathe.
Various things have been suggested as potential causes, or triggers, of the initial damage to the cells lining the alveoli. These include:
Idiopathic pulmonary fibrosis also seems to run in some families. However, in about 4 out of 5 cases, there is no family history of the disease.
(A similar fibrotic lung condition sometimes occurs as a result of exposure at work to certain metals, wood dusts and other chemicals, and as a side-effect to certain medicines. These conditions are not idiopathic, as the cause can be identified. If you have suspected lung fibrosis, your doctor is likely to ask you about your work history to rule out these conditions.)
It is rare. Fewer than 3 in 10,000 people develop this disease. However, it seems to be getting more common. It can affect anybody at any age but it most commonly develops between the ages of 50 and 70. It seems to be more common in men than in women.
Symptoms tend to develop gradually:
As the condition progresses, symptoms can sometimes quickly become worse (called an acute exacerbation). Periods of worse symptoms may be followed by periods where there seems to be some improvement. If the condition becomes severe then heart failure may develop. This is due to the reduced level of oxygen in the blood and changes in the lung tissue, which can cause an increase in pressure in the blood vessels in the lungs. This increase in pressure can put a strain on the heart muscle, leading to heart failure. Heart failure can cause various symptoms including worsening breathlessness and fluid retention.
The above symptoms, combined with crackles heard by a doctor listening to your lungs with a stethoscope, can suggest the diagnosis. A chest X-ray may show a typical scarring pattern in the lungs, suggestive of the disease. Special breathing tests can also show changes that raise suspicion. Your doctor may advise that they refer you to a chest specialist if they suspect that you have idiopathic pulmonary fibrosis.
To confirm the diagnosis, and to assess the severity of the disease, a CT scan of the lung and/or a lung biopsy are usually needed.
A special type of CT scanning, called high-resolution CT (HRCT) scanning, is commonly used. A lung biopsy is where a small sample of lung tissue is taken by a small operation. A keyhole procedure is normally used. The sample is looked at under a microscope. Idiopathic pulmonary fibrosis causes a typical appearance of the alveoli and nearby lung tissue. This can be seen when the biopsy sample is examined. Sometimes the specialist may suggest that they take samples of your lung cells in another way to examine them. This is usually done through a procedure known as a bronchoscopy. A small, flexible telescope is passed down your breathing tubes so that the samples can be collected.
An echocardiogram (an ultrasound examination of your heart) may be done if it is suspected that you have developed heart failure.
At present there is no cure for idiopathic pulmonary fibrosis and the optimal treatment has not yet been found. The aim of treatment is to suppress the symptoms as much as possible.
Because idiopathic pulmonary fibrosis was originally thought to be due to inflammation of the alveoli leading to fibrosis and scarring, treatment has been based on medicines to help suppress (reduce) this inflammation. These included treatments with corticosteroids (steroids) and immunosuppressant medicines such as azathioprine. These medicines are still used to some extent as they can be helpful in some people. Newer medicines are also being studied.
One or more of the following options may be advised to help to improve symptoms, and to slow down the progression of the disease:
Various newer treatments have been tried. These include interferon, N-acetylcysteine and pirfenidone. These newer medicines are thought to work by having an effect on the fibrosis that develops in the disease. However, more trials are needed before the benefit of these medicines can be confirmed.
The progression of the disease can vary greatly. Some people respond to medication which may slow the progression of the disease but, in others, it makes little difference. Some people remain stable for many years after being diagnosed, but others deteriorate much more rapidly. It is difficult to predict at the outset how fast the disease will progress for each affected individual. Lung transplantation has been shown to improve survival in those people for whom it is suitable and so is being increasingly used as a treatment. Newer treatments with medicines may also be shown to be of benefit in the future.