What is Idiopathic Pulmonary Fibrosis (IPF)?

Idiopathic Pulmonary Fibrosis, or IPF, is a serious condition that affects the delicate tissues of the lungs. Normally the lung tissue is soft and flexible which means it is easy to breathe, but in someone with IPF the lung tissue stiffens and becomes damaged from scarring. The process of the scarring of the lungs is called fibrosis, and once it has occurred the tissue does not recover.

  • Idiopathic (means a condition without any known cause)
  • Pulmonary (relating to the lungs or respiratory system)
  • Fibrosis (a rapid increase of fibrous connective tissue – this process occurs naturally in the formation of scar tissue to replace normal tissue lost through injury or infection, but in this instance causes irreversible damage of the lung tissue)

There is no known cause for IPF, however:

  • It is not an infection
  • It is not infectious (caught from other people)
  • It is not a form of cancer
  • It is nothing to do with cystic fibrosis

Click here to learn more about what IPF is and how it is related to other Interstitial Lung Disease's.


Most people develop their IPF symptoms after the age of 60 years and the disease is uncommon in people below the age of 50 years. Men are affected more commonly than women.

The most common symptoms are:

  • Breathlessness, especially when exercising, such as walking up hills or stairs
  • A chronic dry or hacking cough
  • Discomfort in the chest, although rarely is this described as severe pain
  • Finger “clubbing”, which is a change in the shape of the fingernails
  • Fatigue and weakness
  • Loss of appetite
  • Rapid loss of weight

These symptoms are not specific to IPF, meaning that there are many other conditions which can have the same symptoms. In particular, heart failure or chest infection can cause many of the above symptoms. This means IPF can be difficult to diagnose in the early stages of the disease. The symptoms often only become more evident when the disease has already caused considerable damage to the lungs. Other symptoms may be found in other ILDs, such as joint or muscle pain.


Although the cause of IPF is not known, a number of factors are thought to trigger it:

  • Viral infections
  • Gastric-oesophageal reflux (‘heartburn”, with stomach acid entering the lungs in small quantities)
  • Exposure to a variety of occupational dusts and chemical fumes
  • Smoking
Occasionally more than one family member develops IPF, suggesting that genes may be involved in causing the disease.


A limited awareness of the cause and progress of the disease has often made diagnosis difficult and it is common for the condition to be incorrectly diagnosed initially. A diagnosis is usually made by a specialist, after a referral by a general practitioner (GP). How commonly IPF occurs is not clearly known, but a reasonable estimate would be around 5 cases per 10,000 individuals – which means most GPs may encounter a new case about once per decade of full time work.

Most people will have the following investigations:

  • History and physical examination: Talking to the patient and often their family to find any factors in the home or work environment, any medical illnesses that run through the family, any medications, treatments (such as radiotherapy) or any other medical conditions that might make a person at risk of getting ILD. When listening to the lungs with a stethoscope, a doctor may hear crackles (often referred to as “velcro crackles”). However as mentioned above, other conditions can also cause crackles, so they cannot be relied upon for a definite diagnosis.
  • Chest x-ray: This may show signs of the scarring, even early on, so some people will be diagnosed by an abnormal chest x-ray before they develop symptoms.
  • Lung function tests: These are breathing tests to show how well your lungs are working. They are used later to monitor both how bad the disease is, and assess rate of worsening.
  • Pulse oximeter: This test indicates the amount of oxygen carried in the blood.
  • Arterial blood gases: A direct measurement is made of both oxygen and carbon dioxide levels in blood, by taking a sample with a needle and syringe from an artery, usually in the wrist.
  • Blood tests: These are usually done to exclude other causes of ILD (such as rheumatological diseases).
  • CT scan (HRCT): This is a special type of x-ray scan which produces very high resolution pictures of the inside of the lungs.
  • Bronchoscopy: Some people may also require a bronchoscopy, which involves passing a small flexible telescope down into the lungs to collect samples.
  • Surgical lung biopsy: Some patients may also need to have a surgical lung biopsy under general anaesthetic, to make a firm diagnosis of IPF.

Click here to view more detailed information about each of the above investigations.