Mannitol challenge test

What is a mannitol challenge test?

A mannitol challenge test is a breathing test which is used to measure how sensitive your airways are. This will help the doctor to diagnose your lung condition. The test will involve you breathing in a type of powdered sugar called Mannitol and then your lung capacity will be measured by doing a spirometry test (lung function).

If your airways narrow, it means they are hypersensitive (overly sensitive). If your airways do not narrow, they are not hypersensitive.

Why do I need this test?

Your doctor has referred you for a mannitol challenge test to identify if your airways are hypersensitive, which could contribute towards a diagnosis of asthma.

Mannitol challenge test benefits

This is a simple, accurate and non-invasive test that helps us to:

• Diagnose lung conditions
• Monitor the health of your lungs or the development of a lung condition
• Decide your treatment plan

Before the test: how to prepare

Do not use any inhaled respiratory medications or antihistamines and several other medicines before the test because this can affect the results. The table shows for how long you need to stop taking certain medications and substances.

If you are currently using any inhalers or medications not listed, contact us on the number listed on this leaflet. In addition, if you have any of the following, contact us:

• You have a current chest infection
• You are coughing up blood or vomiting
• You have had an aortic or cerebral aneurysm (abnormal swelling of an artery)
• You have had a recent heart attack or collapsed lung
• You have a blood clot
• You have had recent eye, thoracic or abdominal surgery
• You have uncontrolled hypertension or intracranial pressure elevation risk
• You are pregnant or breast-feeding
• You are allergic to mannitol or gelatine
• Recent stroke in the last 6 months

If you are unsure about whether you need to stop any medication or have any questions about this test, please contact us.

If you are feeling unwell, take your inhalers and medication as normal. However please contact us as we may need to reschedule your appointment.

What happens on the day of my test?

When you come in for your test, a physiologist will confirm your identity. They will then check your height and weight, as these measurements will be used to help assess the results of your test. They will ask you about your current health and medical conditions to ensure that it is safe to do the test. They will also explain what happens during the test

How is the mannitol challenge performed?

You will first have a spirometry test. This will involve breathing into a piece of equipment called a spirometer which will measure your lung capacity. This measurement will be used as your baseline for the mannitol challenge test.

You will then be asked to inhale increasing amounts of Mannitol via an inhaler device and after each dose spirometry will be performed again to measure your response to the mannitol. The doses of mannitol will continue until you either reach the maximum dose or your physiologist sees a significant response to the mannitol.

Once this point has been reached, the physiologist will give you a nebuliser (a device that delivers high doses of a medicine quickly and easily) containing salbutamol. You will then take a 15-minute break to allow for the medication to fully work and then spirometry will be done again to make sure that your lung function is back to normal before you leave. In total, the Mannitol test will take 90 minutes to complete.

Test results

Your results will be sent to your referring doctor for them to review and discuss with you at your next Chest clinic appointment.

Mannitol challenge test risks

Due to the nature of the tests and the exertion required, some patients may feel dizzy or faint during testing. Coughing is also common. Serious complications are rare, and risks will be kept to a minimum by your physiologist.

• The Mannitol might make you cough when you breathe it in. If your airways are hypersensitive, it will cause them to narrow, so you may feel more wheezy, breathless or tight chested. We will give you a nebuliser at the end of the test to help ease your breathing.
• The spirometry test may make you feel dizzy, breathless or faint.
• If we give you a nebuliser to use at the end of the test, this may cause palpitations or a fast heart rate.
• There is a small risk of side effects. These include headaches, chest tightness, sore throat, light-headedness, nausea, runny nose, vomiting or dizziness.
• There is an extremely rare risk of allergic reaction.

If you have any concerns about the risks, please speak to your physiologist prior to starting the test.

Mannitol challenge test alternatives

You can have lung function tests, x-rays and scans; however, the challenge test is more accurate at helping to diagnose active asthma. It is the only test that directly looks at the sensitivity of your airways.