Interstitial lung disease (ILD)

What is interstitial lung disease (ILD)?  

Interstitial lung disease (ILD) describes a group of over 200 conditions that cause inflammation, stiffening and progressive scarring of the lung tissues – sometimes referred to as pulmonary fibrosis.  

The damage caused by ILD to lung tissues around the alveoli – the ‘air sacs’ of the lungs – makes breathing and getting oxygen into your bloodstream increasingly difficult. This reduces vital oxygen supplies to your organs, affecting how well they work.

Unfortunately, lung damage caused by ILD can be irreversible, and the effects worsen. It is estimated that as many as 10,000 new patients are diagnosed with ILD in the UK each year.

Types of interstitial lung disease

Some forms of interstitial lung disease are more common than others.  

Idiopathic pulmonary fibrosis 

Also known as IPF, idiopathic pulmonary fibrosis is the most common interstitial lung disease. It typically affects patients over the age of 60 and is rare in people under 50.  

No one knows what causes IPF, but studies link it to various factors, including exposure to certain types of dust, such as metal or wood dust, viral infections, smoking and gastro-oesophageal reflux disease.  

It’s also more common in those with a family history of IPF. Around 1 in 20 people with the condition have another family member with it too.  

Pulmonary sarcoidosis 

Pulmonary sarcoidosis is a respiratory condition caused by the growth of many tiny clusters of inflammatory cells called granulomas. These granulomas can develop in any part of the body but most often form in the lungs and lymph nodes.

Untreated pulmonary sarcoidosis can lead to permanent scarring, making breathing difficult.  

Unfortunately, the cause of the formation of granulomas is not known. But it’s thought that bacteria, viruses or chemicals could be a trigger. Having close relatives with the condition can also increase your risk of developing the condition.

Other types of interstitial lung disease 

Our lung specialists have extensive experience in managing all types of interstitial lung disease, including: 

• alveolar microlithiasis 
• connective tissue disease-associated lung disease 
• cryptogenic organising pneumonia  
• drug-induced interstitial lung disease 
• hypersensitivity pneumonitis 
• idiopathic pulmonary fibrosis  
• Langerhans’ cell histiocytosis 
• lymphangioleiomyomatosis 
• non-specific interstitial pneumonitis 
• pleuroparenchymal fibroelastosis 
• pulmonary alveolar proteinosis 
• pulmonary sarcoidosis  
• vasculitis-associated lung disease 

Symptoms of interstitial lung disease 

The unpredictable progression of interstitial lung disease means symptoms vary from person to person.  

Some people will experience mild symptoms for a long time, suddenly worsening. Others may see a slow and gradual worsening of their symptoms. For some, their disease doesn’t worsen, and the symptoms remain the same. Every journey is different. 

Some of the most common symptoms of interstitial lung disease include: 

• shortness of breath that gets worse with movement or activity 
• dry, hacking cough that doesn’t produce phlegm 
• extreme tiredness and weakness 
• no appetite 
• unexplained weight loss 
• mild pain in the chest  
• laboured breathing, which appears fast and shallow 
• bleeding in your lungs, which may include spots of blood on a tissue when you cough 
• clubbed fingertips or nails
  

Remember, these symptoms can also point to other health conditions, so if you experience any of them, you must speak to your doctor to determine their cause.

Causes of interstitial lung disease 

In some cases, the cause of interstitial lung disease is known. For example, having an autoimmune condition such as rheumatoid arthritis or systemic sclerosis increases the risk of developing interstitial lung disease. Exposure to airborne triggers such as feathers or mould can also increase the risk – this is the case in hypersensitivity pneumonitis. However, when there is no identifiable cause, the condition is often diagnosed as idiopathic pulmonary fibrosis (IPF) which is a progressive fibrotic (scarring) condition. 

Factors that make developing the condition more likely include: 

• age: interstitial lung disease is more common in adults. However, some infants and children can develop it 
• exposure to workplace and environmental pollutants: these include silica gel, asbestos, grain dust and animal or bird droppings 
• gastroesophageal reflux disease (GERD): uncontrolled acid reflux or indigestion has been associated with an increased risk of interstitial lung disease 
• medical conditions like sarcoidosis and autoimmune disorders like rheumatoid arthritis, systemic lupus erythematosus and systemic sclerosis 
• smoking: some types of interstitial lung disease are more likely to develop in people who have smoked in the past. Active smoking may also make the condition worse 
• specific medications: treatments such as those used to treat irregular heartbeats, some antibiotics and chemotherapy drugs for cancer 

Complications of interstitial lung disease 

Interstitial lung diseases can lead to severe and even life-threatening complications if left untreated, including: 

• progressive pulmonary fibrosis (lung scarring) 
• high blood pressure in your lungs, called pulmonary hypertension 
• right-sided heart failure because the right ventricle of the heart must work hard to force blood through obstructed pulmonary arteries
• respiratory failure
  

Doctors usually recommend annual ‘flu and pneumonia vaccinations if you have interstitial lung diseases because these illnesses can worsen symptoms of ILD. The vaccinations can help prevent ‘flu or pneumonia and their complications, such as ear infections, lung infections and meningitis.  

How is interstitial lung disease diagnosed? 

Your doctor can often diagnose interstitial lung disease without invasive testing.  

Initially, they will talk to you about your symptoms and medical history. They may also do a physical examination and request diagnostic scans, including blood tests, a CT scan or echocardiogram.  

Following the examination and diagnostic scans, they will probably organise pulmonary function tests to measure how much air moves in and out of your lungs.  

In some cases, our team may recommend a lung tissue analysis where they take a small amount of lung fluid and sometimes tissue and send it to a laboratory to be looked at under a microscope.  

Doctors use various techniques to take a sample of lung tissue, including: 

• a bronchoscopy, where they insert a thin tube via the nose or throat into the lungs 
• bronchoalveolar lavage, which involves an injection of salt water into the lungs 
• a cryobiopsy, where they take a sample of lung tissue through the bronchoscope 
• surgical biopsy, where they take a sample surgically

Interstitial lung disease treatment 

There is currently no cure for interstitial lung disease and no ‘one-size-fits-all’ treatment for it.  

Instead, treatment will vary depending on your condition’s suspected cause and severity. And since most lung damage is irreversible, we will focus treatment on preventing any more scarring, managing your symptoms and maintaining your quality of life by keeping you as healthy and active as possible.  

Give up smoking and vaping 

If you smoke or vape, the first thing we will ask you to do is to stop. Smoking is a risk factor in some types of interstitial lung disease development, but it can worsen the disease. Our team will be happy to help you stop smoking, and it is always helpful to let friends and family know so they can also offer their support. 

Oral medications 

Doctors prescribe many people ILD medications that help reduce inflammation in the lungs including prednisolone (a steroid) and other drugs which suppress their immune system. Some oral medications can also protect the lungs from more damage. Antifibrotic (anti-scarring) medications can slow down the rate of future lung scarring in patients with idiopathic pulmonary fibrosis and other types of ILD which result in progressive pulmonary fibrosis. 

Oxygen therapy 

We can provide a portable oxygen tank that delivers oxygen through tubes into your nose. This therapy boosts your overall oxygen levels when they are low.  

Pulmonary rehabilitation  

Certain exercises can help you breathe more easily. We have specialist respiratory physiotherapists at Royal Brompton and Harefield hospitals who help patients with interstitial lung disease. 

Lung transplant 

In some cases, a lung transplant may be possible.