Asthma Diagnosis: Exploring FeNO Tests and Related Treatments
The FeNO (Fractional exhaled nitric oxide) test is a quick, non-invasive method used by doctors to support the diagnosis of asthma, especially in children aged 5 years and older, and adults. This test requires exhaling into a handheld device and inhaling slowly and deeply.
The diagnostic accuracy of the FeNO test varies depending on the population, but it generally offers good specificity, especially at higher FeNO levels.
In Children
For children, a normal FeNO reading is below 20 ppb, intermediate is 20-35 ppb, and high is more than 35 ppb. FeNO levels below 20 ppb indicate unlikely eosinophilic inflammation and corticosteroid responsiveness, whereas levels above 35 ppb suggest probable eosinophilic inflammation and likely responsiveness to corticosteroids. FeNO monitoring in children and adolescents can also predict asthma relapse after discontinuing inhaled corticosteroids, often before clinical symptoms appear.
In Adults
In adults, according to European Respiratory Society (ERS) 2022 guidelines, a FeNO cut-off of 40 parts per billion (ppb) balances sensitivity and specificity for asthma diagnosis, while a cut-off of 50 ppb has a high specificity >90%, strongly supporting asthma diagnosis. However, FeNO below 40 ppb does not exclude asthma, and elevated FeNO alone does not confirm it.
Several factors can affect the FeNO test results. Age is one such factor, with different cut-offs and interpretations used for children vs. adults. Eosinophilic airway inflammation, corticosteroid treatment, smoking status, atopy/allergic rhinitis, environmental factors, and technical and procedural aspects also influence the results.
The FeNO test is primarily useful to identify eosinophilic airway inflammation characteristic of asthma rather than general airway obstruction. It is complementary to pulmonary function tests.
An allergist may request a FeNO test to diagnose or monitor asthma or determine the effectiveness of anti-inflammatory steroid medications. The FeNO test can help medical professionals track levels of airway inflammation over time. It is a type of lung function test that measures the level of nitric oxide gas in exhaled air. High FeNO readings in both adults and children indicate airway inflammation that may be due to underlying asthma.
People should avoid certain factors at least 1 hour before their FeNO test, such as smoking, vaping, alcohol consumption, carbonated beverages, caffeine consumption, and consumption of highly processed foods. The guidelines for FeNO test results in adults and children differ.
Doctors may use FeNO test results to guide treatments for asthma, particularly for individuals with uncontrolled and persistent asthma, those requiring additional anti-inflammatory treatment, and those with a genetic predisposition to allergic diseases such as asthma, allergic rhinitis, and eczema. Cells produce nitric oxide gas in response to inflammation, particularly in certain types of asthma.
In conclusion, the FeNO test provides moderate sensitivity and high specificity for asthma diagnosis with specific cut-offs (40–50 ppb adults, 20–35 ppb children), and its accuracy improves when combined with clinical assessment and other lung function tests. Multiple biological and technical factors must be considered to interpret FeNO levels accurately.
- The FeNO test is a diagnostic tool for asthma, particularly in children and adults.
- It requires individuals to exhale into a handheld device and inhale slowly and deeply.
- In children, a normal FeNO reading is below 20 ppb, while in adults, it is below 40 ppb according to ERS 2022 guidelines.
- Intermediate levels for children are 20-35 ppb, and for high levels, it's more than 35 ppb for children and 50 ppb for adults.
- FeNO levels in children can predict asthma relapse after discontinuing inhaled corticosteroids.
- In adults, a FeNO cut-off of 40 ppb balances sensitivity and specificity for asthma diagnosis, while 50 ppb has a high specificity.
- The FeNO test is useful for identifying eosinophilic airway inflammation characteristic of asthma rather than general airway obstruction.
- It is complementary to pulmonary function tests and can help medical professionals track levels of airway inflammation over time.
- Several factors like age, eosinophilic airway inflammation, corticosteroid treatment, smoking status, atopy/allergic rhinitis, environmental factors, and technical and procedural aspects can affect the FeNO test results.
- People should avoid certain factors like smoking, vaping, alcohol consumption, carbonated beverages, caffeine consumption, and consumption of highly processed foods at least 1 hour before the test.
- The FeNO test is requested by allergists to diagnose or monitor asthma or determine the effectiveness of anti-inflammatory steroid medications.
- The accuracy of the FeNO test improves when combined with clinical assessment and other lung function tests.
- High FeNO readings indicate airway inflammation that may be due to underlying asthma in both adults and children.
- Asthma treatments can be guided by FeNO test results, particularly for individuals with uncontrolled and persistent asthma.
- The FeNO test measures the level of nitric oxide gas in exhaled air, which cells produce in response to inflammation, particularly in certain types of asthma.
- The guidelines for FeNO test results in adults and children differ.
- The FeNO test is a part of health and wellness conversation, considering it's related to chronic diseases and medical conditions.
- Workplace-wellness programs can benefit from incorporating information about respiratory health, including the FeNO test.
- FeNO test results can help doctors manage asthma better, leading to improved workplace productivity and reduced absenteeism.
- Climate change may impact asthma symptoms and the FeNO test results, considering pollution and air quality changes.
- Manufacturing industries contribute to air pollution, which can affect FeNO test results and contribute to asthma development.
- Mental health is crucial in managing chronic diseases like asthma, as stress can trigger symptoms.
- Skin-care products can help reduce allergic reactions, which may indirectly help manage asthma symptoms.
- Therapies and treatments, including therapies for mental health, play a significant role in asthma management.
- Nutrition plays a vital role in asthma management, as certain foods can help reduce inflammation and improve lung function.
- The finance industry can develop innovative financing solutions for companies investing in environmental-science projects to combat climate change and improve air quality.
- Energy-efficient technologies can help reduce air pollution, benefiting those with asthma and improving overall environmental health.
- Space and astronomy can inspire and educate people about the importance of preserving Earth's health and mitigating climate change, which, in turn, benefits asthma management.
