1 in 20 people with asthma have severe asthma

Tests for severe asthma

Various tests are used to find out whether you have severe asthma

Getting a diagnosis of severe asthma can take time. In fact 55 per cent of people in an Asthma UK survey said that after being initially diagnosed with asthma it had taken a few years for them to be diagnosed with severe asthma.

If you’re taking your asthma medicines exactly as prescribed and using the right inhaler technique, but you’re still getting symptoms, your GP or asthma nurse may refer you to an asthma specialist. They will try to work out what’s going on by answering these questions:

You might have had tests to diagnose and monitor your asthma already, but to confirm or rule out a diagnosis of severe asthma you may need some extra tests.

You probably won’t need all these tests, though. Your asthma specialist will explain which ones you need and why.

“Everyone with asthma is different so the tests you’ll need will depend on your individual asthma symptoms, medical history, family history and any other conditions you have,” says Asthma UK’s in-house GP Dr Andy Whittamore. “And because your asthma symptoms can vary over time, you may need to have these tests more than once to help your asthma specialist make the right diagnosis.”

"Being diagnosed with severe asthma was a really drawn out process, but it was such a relief to finally know what was wrong."  - Celena Dell, 34

This section will help you understand what happens if you have these tests and why they're done.

Blood tests

What are they?

Most people who see an asthma specialist are sent for blood tests.

When are they used?

Asthma specialists use these tests to:

  • rule out other causes of your symptoms
  • look for signs of allergic inflammation in your blood
  • check that certain organs, such as your liver and kidneys, are working properly.

What do the results show?

"The results may show that you don't have severe asthma and that your symptoms are caused by something else, such as anaemia (low levels of iron) or an infection," says Asthma UK’s in-house GP Dr Andy Whittamore. "They may also give clues about how to manage your asthma because if allergic inflammation is found this shows that treatments which ‘switch off’ the allergic response may work well for you. And knowing that organs such as your liver and kidneys are working well means that it's possible to prescribe certain treatments that can't be used if they're not working well."

Sputum induction test



What is it?


This painless test involves collecting a fresh sample of sputum (a mixture of saliva and mucus) from your lungs so it can be analysed in a laboratory. You will be asked to breathe in different concentrations of slightly salty water through a nebuliser and then cough them up to produce a sample.

When is it used? 

You may be asked to do this test if your asthma specialist is trying to work out why you have underlying inflammation in your airways.

What do the results show?

Your sputum can help your asthma specialist find clues to what’s causing the underlying inflammation in your airways – for example, the number of eosinophils (a type of white blood cell associated with allergy) will help your asthma specialist see what’s causing the underlying inflammation and what treatments might help it.

24-hour pH monitoring and manometry tests

What are they?

Both of these tests check for signs of gastro-oesophageal reflux disease (GORD), when acid leaks out of your stomach and up into your oesophagus (the tube that takes food to the stomach) causing heartburn or indigestion. Heartburn is an uncomfortable burning sensation in the chest. Indigestion is a pain or discomfort in the stomach and/or under the ribs.

24-hour pH monitoring involves passing a thin tube containing a sensor up your nose and down your throat to measure the acidity level (pH) in your throat over a 24-hour period. This tube is usually attached to a recording device that's worn on your waist. Every time you become aware of symptoms you'll be asked to press a button on the device and write down your symptoms in a diary. To make sure the test results are accurate you’ll be encouraged to eat and drink as normal.

Manometry tests
help your asthma specialist work out how well the ring of muscle at the end of your oesophagus is working by measuring the pressure in your oesophagus. It involves passing a small tube containing pressure sensors up your nose and down into your oesophagus.

When are they used?

If your asthma specialist thinks GORD could be making your asthma symptoms worse even if you’re not getting the typical symptoms, they may want to do these tests.

What do the results show?

24-hour pH monitoring measures the acidity level (pH) in your oesophagus. Manometry tests show how well your oesophagus is working. Both tests can help your asthma specialist work out if you have GORD.

"There are people whose asthma gets worse due to acid reflux, but who don't have any of the typical acid reflux symptoms, such as heartburn or indigestion," says Asthma UK’s in-house GP Dr Andy Whittamore. "It’s useful for your asthma to know whether you have GORD because stomach acid irritates airways and causes inflammation, making asthma symptoms worse. These test results help to rule out or confirm that acid reflux is a cause of some or any of the asthma symptoms."

Chest X-ray

What is it?

A chest X-ray is a quick and painless procedure usually done in a hospital by a radiographer that produces images of the inside of your chest.

When is it used?

Chest X-rays are commonly used to check that there isn’t anything else causing your asthma symptoms.

What do the results show?

The results will help to make sure that your symptoms aren't being caused by an infection such as pneumonia, a blockage or, in rare instances, a tumour. Remember that having this test doesn't mean your specialist thinks you have lung cancer, it's just a way of ruling it out.

CT scan

What is it?

A computerised tomography (CT) scan uses X-rays and computers to give a detailed 360-degree image of the inside of your lungs. Carried out in a hospital, the ring-shaped scanner rotates around your chest in small sections. Some clinics will also perform a CT scan of your nose and sinuses as they can play a big role in the symptoms of some people with asthma.

The scanner doesn't surround your whole body at once, so it's unlikely you'll feel claustrophobic.

When is it used?

A CT scan of your chest is increasingly used alongside a chest X-ray to check that there’s nothing else causing your symptoms.

What do the results show?

"A CT scan of the chest allows your asthma specialist to carry out a more complete assessment of your lungs than an X-ray alone, and may help them look for and exclude other conditions such as bronchiectasis (a long-term condition where your airways become abnormally widened, leading to a build-up of excess mucus), diseases that affect the tissues that support the airways, and clots in your lungs," says Asthma UK’s in-house GP Dr Andy Whittamore. 

ECG

What is it?

ECG stands for electrocardiogram. This is a simple test that uses sensors attached to your chest to check the electrical signals your heart produces each time it beats.

When is it used?

An ECG is used to check your heart's rhythm and electrical activity when your asthma specialist wants to see whether your heart is the cause of your severe asthma symptoms. Your asthma specialist will consider your age, medical history and symptoms to decide whether you need this test.

What do the results show?

"The results of an ECG show your asthma specialist whether your heart is healthy enough to prescribe certain medicines and also tell them if there any other possible causes of your asthma symptoms, such as an irregular heartbeat, an enlarged heart or previous damage to your heart muscles," says Asthma UK’s in-house GP Dr Andy Whittamore.

Bronchoscopy

What is it?

A bronchoscopy involves passing a thin, flexible tube down your throat and into your airways. The tube has a light and a camera on the end to allow your asthma specialist to see right into your airways. You’ll be given a sedative beforehand and the back of your throat will be numbed so it’s less uncomfortable.

The procedure is usually performed in an outpatients clinic so you won't have to stay in hospital overnight.

When is it used?

This test is used when your asthma specialist wants to see inside your airways or needs to take a small sample of phlegm or tissue for examination. "There are less invasive options available, such as a CT scan, so it’s used less often these days,” says Asthma UK’s in-house GP Dr Andy Whittamore. “If you need one, your asthma specialist will explain why.”

What do the results show?

This test will help your asthma specialist rule out other causes of your asthma symptoms. It can also help pin down the specific pattern of your asthma if other tests haven’t given enough information.

Nasendoscopy

What is it?

This test uses a thin microscope to allow your asthma specialist to see what’s going on in your nasal passages. It's usually performed in an outpatients clinic. 

When is it used?

"A nasendoscopy can help to detect problems in your nose, sinuses and even your throat that can lead to chest symptoms and so make your asthma symptoms worse," says Asthma UK’s in-house GP Dr Andy Whittamore. "This test is usually only done if they think your nose and sinuses may be triggering some of your symptoms.”

What do the results show?

Because conditions that affect your sinuses can trigger asthma symptoms, the results of this test can show whether or not you need treatment for your sinuses to help your asthma symptoms.  

Hyperventilation questionnaire

What is it?

The hyperventilation questionnaire most often used by the NHS is the ‘Nijmegen Questionnaire’, which asks you how often you have had 16 different symptoms such as faster or deeper breathing, dizzy spells, blurred vision and palpitations and gives you points for each one.

When is it used?

If your asthma specialist suspects you may be breathing too fast they may do this test. "Hyperventilating can sometimes make the symptoms of asthma worse," says Asthma UK’s in-house GP Dr Andy Whittamore. "This is why it’s important to spot and treat this problem to help control your asthma symptoms."

What do the results show?

A score of over 23 out of 64 suggests you may be hyperventilating. According to the latest guidelines health professionals use on the management of asthma (BTS/SIGN), people who hyperventilate may benefit from physiotherapist-supervised breathing techniques such as the Papworth method and Buteyko Breathing Technique. These can improve your asthma symptoms and quality of life. In adults they can also reduce the amount of asthma medicines you need, although they don’t have an effect on lung function or inflammation.

Symptom and quality of life scores

What are they?

These tests involve filling out questionnaires to find out what symptoms you’re experiencing and the different ways asthma may be affecting your life. In an Asthma UK survey, 91 per cent of people said their severe asthma had an impact on everyday things, such as their ability to exercise, their family and social life, their work or school life and their holidays. In the same survey 82 per cent of people said they'd experienced sleep loss and 66 per cent had gained weight.

When are they used?

"If your asthma symptoms mean you can’t do things you used to be able to do, such as exercise or play with your children, these scores will help your asthma specialist find out exactly what is happening to you and how it is affecting your life," says Asthma UK’s in-house GP Dr Andy Whittamore. "They’re also a useful way to monitor how well your asthma treatments are working."

What do the results show?

The results can give your asthma specialist a clearer picture of your asthma symptoms, how they may be limiting your activities and how you’re coping with the challenges of having frequent asthma symptoms. They can also be used to work out your response to longer-term treatment trials.

Depression and anxiety scores

What are they?

These questionnaires are used to find out how having severe asthma is affecting you emotionally. In an Asthma UK survey, 68 per cent of people with severe asthma said they’d had anxiety and 52 per cent of people with severe asthma said they felt depressed.

When are they used?

"Because asthma symptoms that affect your quality of life can be worrying and get you down it’s important for your healthcare team to understand how you’re feeling," says Asthma UK’s in-house GP Dr Andy Whittamore. "If you’re seeing an asthma specialist to diagnose or rule out severe asthma, they will usually consider screening you for anxiety and depression – often using this questionnaire." 

What do the results show?

"Evidence shows that people with low mood or anxiety can find it harder to control their asthma symptoms," says Dr Whittamore. "It’s important that your asthma specialist and healthcare team have a good understanding of how you’re feeling so they can give you the support you need."

Last updated November 2016

Next review due November 2019