What is a FeNO Test?
- Your airway tubes can become inflamed in asthma, and this produces a chemical called nitric oxide.
- The FeNO test measures how much nitric oxide is in your breath when you breathe out and helps us understand how much inflammation you have in your lungs.
- The test may help to diagnose asthma or to see how well treatments are working.
- FeNO can be high for other reasons (e.g. hay fever) and is not high in all types of asthma.
What should I avoid prior to the test?
Several things can affect the results of the FeNO Test.
- 24 hours before – Avoid alcohol consumption
- 12 hours before – Avoid smoking
- 12 hours before – Avoid foods high in nitrates such as rocket, green beans, spinach, leek, spring onion, radish, cucumber, carrot, beetroot, Chinese cabbage, potato, turnips, garlic, cabbage, sweet pepper, green pepper.
- 6 hours before DO NOT use your preventer inhaler (containing inhaled steroid)
- 1 hour before – Avoid eating, exercise and using your inhalers.
What happens during a FeNO test?
- You can sit down for the test and first youwill be asked to take a deep breath in with your mouth open then breathe out slowly and steadily into the mouthpiece for about 10 seconds.
- the test is easy to do but you may need to do it more than once to get a result.
- The test usually takes less than 5 minutes to perform.
