Asthma can be complex to confirm and even more challenging to manage without the right tools. You may already know about breathing tests like spirometry, but those don’t always reveal the whole picture.
The FeNO test measures inflammation in your airways, giving your doctor clear insight into whether asthma is present and how well your treatment is working.
At Gwinnett Pulmonary, this simple, noninvasive test takes only a few minutes and provides immediate results. By checking the level of nitric oxide in your breath, the test helps identify the type and severity of airway inflammation.
This information enables your care team to tailor a treatment plan that is most effective for your condition. Using FeNO testing regularly also helps track how your body responds to medication.
If inflammation levels stay high, adjustments can be made before symptoms worsen.
The FeNO test measures nitric oxide in your breath to help identify airway inflammation. It is a quick, non-invasive diagnostic procedure that supports asthma diagnosis, tracks treatment response, and distinguishes asthma from other respiratory conditions.
Fractional Exhaled Nitric Oxide (FeNO) refers to the amount of nitric oxide gas you release when you breathe out. This gas is naturally produced in your airways.
When inflammation is present, such as in allergic or eosinophilic asthma, nitric oxide levels rise. The FeNO test captures this measurement in parts per billion (ppb).
At Gwinnett Pulmonary, you simply exhale into a handheld device for about 10 seconds. The device analyzes your breath and provides immediate results.
This direct measurement gives your doctor insight into whether inflammation is driving your symptoms.
Traditional asthma tests, such as spirometry or peak flow, measure how well air moves through the lungs. These tests focus on airflow limitation but may not detect the inflammation causing your symptoms.
The FeNO test differs because it assesses underlying airway inflammation. This makes it especially useful when other tests show normal lung function, but you still have asthma symptoms.
Unlike blood tests or sputum analysis, FeNO testing is non-invasive and does not require lab processing. Results are available in minutes, so your doctor can adjust your treatment plan during the same visit.
Because it measures inflammation directly, FeNO testing helps guide the use of inhaled corticosteroids. If your levels are high, your doctor may recommend adjusting your medication to control inflammation better.
You may benefit from FeNO testing if you experience symptoms such as coughing, wheezing, or shortness of breath, but your diagnosis remains unclear. The test is approved for use in adults and children over the age of 5, making it applicable across a wide range of age groups.
It is also helpful if you already have asthma. Regular monitoring can help determine whether your current medications are effective.
Rising FeNO levels can signal poor control even before symptoms worsen. FeNO testing is especially valuable if allergies trigger your asthma.
It can detect increases in nitric oxide after allergen exposure, helping your doctor adjust your treatment. At Gwinnett Pulmonary, this test is often used to personalize care and reduce unnecessary medication use.
The FeNO test measures nitric oxide in your exhaled breath to detect airway inflammation. It utilizes a handheld device that provides fast results, enabling your doctor to understand how well your asthma is controlled and whether adjustments to your treatment are needed.
The FeNO test is a non-invasive and straightforward procedure. You sit comfortably and breathe into a FeNO testing machine through a disposable mouthpiece.
A technician will guide you to take a deep breath in, then exhale slowly and steadily at a controlled pace. The device tracks the flow of your breath and measures the nitric oxide concentration in real time.
Most tests require you to exhale for about 10 seconds. To confirm accuracy, you may need to repeat the process one or two times.
The machine then calculates an average reading. The entire test usually takes less than 10 minutes.
No needles, blood work, or invasive procedures are involved, making it suitable for both adults and children.
Your results are given in parts per billion (ppb). These numbers indicate the amount of nitric oxide present in your airways.
Low FeNO levels typically indicate minimal or no airway inflammation. Higher levels often indicate ongoing inflammation, especially in allergic or eosinophilic asthma.
Your doctor will not rely solely on this number. They will compare your symptoms, medical history, and other test results with your condition to determine if your treatment plan needs to be adjusted.
Several factors can influence FeNO levels, which is why proper preparation is crucial.
Other variables include age, height, and recent respiratory infections. Children often have different baseline levels of nitric oxide compared to adults.
To obtain the most reliable results, avoid smoking, heavy exercise, and consuming nitrate-rich meals for at least one hour before testing. Always inform your healthcare provider about all medications you are currently taking.
The FeNO test measures nitric oxide in your breath, which reflects inflammation in your airways. This information helps identify the type of asthma you may have, determine whether inflammation is present, and separate asthma from other conditions with similar symptoms.
Asthma often involves airway inflammation, particularly in cases of allergic or eosinophilic asthma. The FeNO test measures nitric oxide levels in exhaled breath, which rise when inflammation is active.
High readings usually suggest eosinophilic airway inflammation, a common cause of wheezing, coughing, and shortness of breath. Low readings may indicate that inflammation is under control or that your symptoms are not caused by eosinophilic asthma.
Unlike spirometry, which measures airflow, FeNO directly reflects inflammation. This makes it worthwhile when your breathing tests appear normal, but you still have asthma symptoms.
Your doctor can use this data to determine whether inhaled corticosteroids or other anti-inflammatory medications are likely to be effective.
Asthma is not the same for everyone. Some people have allergic asthma, while others have eosinophilic asthma or forms less tied to inflammation.
Identifying these asthma phenotypes is essential because each responds differently to treatment. FeNO testing helps distinguish eosinophilic asthma, where nitric oxide levels are often higher.
This is especially useful if you have a persistent cough or wheezing despite regular lung function tests. By understanding your phenotype, your doctor can tailor treatment.
For example:
This approach helps avoid unnecessary medication and ensures you receive the most effective care tailored to your specific type of asthma.
Respiratory symptoms such as wheezing, coughing, or shortness of breath can be caused by conditions other than asthma. Chronic bronchitis, COPD, or infections may cause similar problems but do not always involve the same type of airway inflammation.
FeNO testing helps separate asthma from these conditions by detecting eosinophilic inflammation. If your FeNO levels are elevated, it supports a diagnosis of asthma rather than another lung disorder.
Because the test is quick and non-invasive, it can be performed concurrently with spirometry and a medical history review. Together, these results give your doctor a clearer picture of whether asthma is the cause of your breathing difficulties.
This distinction is important because asthma treatments often differ from those used for other respiratory diseases.
Using a FeNO test provides a direct way to measure airway inflammation, a key factor in asthma. By tracking nitric oxide levels in your breath, you and your doctor can make informed choices about treatment, medication adjustments, and the prevention of flare-ups.
FeNO monitoring helps you see how well your asthma treatment is working. When you use anti-inflammatory medications, such as inhaled corticosteroids, your FeNO levels usually decrease.
A lower reading often shows that your airways are less inflamed and that your treatment is effective. If your FeNO test results remain high, it may indicate that your current plan is not effectively controlling inflammation.
This information helps your doctor determine whether to adjust your medication or investigate other potential triggers. Regular testing also provides you with measurable feedback.
Instead of relying only on symptoms, you can track changes in airway inflammation over time. This makes your asthma management more precise and less dependent on guesswork.
Key benefits of tracking response:
Inhaled corticosteroids (ICS) are the primary anti-inflammatory treatment for asthma. FeNO testing helps guide how much of this medication you may need.
High FeNO levels often indicate that more ICS is required, while low levels suggest your current dose is adequate. This approach prevents both under-treatment and over-treatment.
If your FeNO levels are consistently low, your doctor may reduce the dose to avoid unnecessary side effects. On the other hand, rising levels may signal the need for more substantial or more frequent use of corticosteroid therapy.
FeNO monitoring also helps identify patients who respond best to ICS. If your FeNO levels do not change significantly with corticosteroids, your asthma may not be driven by eosinophilic inflammation, and an alternative treatment approach may be more effective.
Practical uses include:
Asthma exacerbations, or flare-ups, often occur when airway inflammation increases before symptoms appear. FeNO testing can detect these changes early by showing rising nitric oxide levels.
This allows you and your doctor to act before a full attack develops. For example, if your FeNO results climb above your usual range, your doctor may adjust your medication or recommend closer monitoring.
This proactive step helps reduce the risk of emergency visits and hospitalizations. Children and adults alike benefit from early detection.
Since symptoms like cough or wheeze may not always accurately reflect the level of inflammation, FeNO monitoring provides a more reliable measure.
Identifies inflammation before symptoms worsen
Supports timely medication adjustments
Reduces the chance of severe asthma attacks
At Gwinnett Pulmonary, FeNO testing is used as part of a structured approach to asthma care. The test provides precise measurements of airway inflammation, enabling your pulmonologist to make informed decisions about diagnosis, treatment, and ongoing monitoring.
Gwinnett Pulmonary utilizes FeNO testing as one component of a comprehensive respiratory care plan. The test measures nitric oxide in your breath, which reflects inflammation in your airways.
This helps identify whether your asthma is driven by eosinophilic inflammation, a common type linked to allergic asthma. Your pulmonologist uses this information to decide if anti-inflammatory medications, such as inhaled corticosteroids, are appropriate.
By tracking changes in your FeNO levels, your care team can see if the treatment is reducing inflammation or if adjustments are needed. The test is quick, painless, and provides results during your visit.
This immediate feedback helps guide decisions without delay. It also reduces the likelihood of unnecessary medication changes, as treatment is based on direct evidence of airway inflammation rather than solely on symptoms.
FeNO testing does not replace traditional lung function tests; instead, it works alongside them. At Gwinnett Pulmonary, your evaluation may also include spirometry or other pulmonary function tests that measure airflow, lung volume, and capacity.
Spirometry shows how well you can move air in and out of your lungs, while FeNO measures airway inflammation. Together, these tools give a more complete picture of your lung health.
| Test | What It Measures | Why It Matters |
| FeNO | Nitric oxide in exhaled breath | Detects airway inflammation |
| Spirometry | Airflow and lung volume | Identifies obstruction or restriction |
By combining results, your pulmonologist can tell whether symptoms are caused by inflammation, airflow limitation, or both. This distinction is crucial because it helps avoid unnecessary medication increases when symptoms are not linked to inflammation.
Your FeNO test at Gwinnett Pulmonary is tailored to your individual needs. The process usually takes less than 10 minutes and involves breathing into a handheld device while a technician guides you.
Results are available almost immediately in parts per billion (ppb). Your doctor reviews the numbers in the context of your symptoms, history, and other test results.
For adults, a FeNO level above 25 ppb often suggests ongoing airway inflammation. For children, the threshold is typically 20 parts per billion (ppb).
If your FeNO levels decrease with treatment, it indicates that your medication is effective. If levels remain high, your pulmonologist may adjust your therapy, review your inhaler technique, or investigate other potential causes of your symptoms.
FeNO testing provides valuable information about airway inflammation; however, results can be influenced by several factors. You need to understand these influences to avoid misinterpretation and to ensure the test supports accurate decisions about your respiratory health.
FeNO levels do not always give a clear answer. A high reading may suggest airway inflammation, but it does not confirm asthma on its own.
Other conditions, such as allergic rhinitis or chronic cough, can also increase nitric oxide levels. Low FeNO values can also be misleading.
Some people with asthma, especially those with non-eosinophilic types, may still show expected results. This means you cannot rule out asthma only by looking at FeNO.
Doctors often combine FeNO with spirometry, peak flow, or bronchoprovocation tests to improve accuracy. Tracking FeNO over time, rather than relying on a single test, can also help reveal patterns linked to asthma.
Specific treatments and daily habits can lower or raise FeNO numbers. Inhaled corticosteroids often reduce FeNO, which can make inflammation seem less severe than it really is if you recently used them.
On the other hand, stopping steroids may cause levels to rise quickly. Lifestyle factors also matter.
Smoking, recent viral respiratory infections, and consuming nitrate-rich foods, such as leafy greens, can affect your results. Age, sex, and body size can also influence baseline FeNO levels.
Due to these variables, your test results should be interpreted in the context of your medical history, recent treatments, and current symptoms. This helps avoid false reassurance or unnecessary concern.
FeNO is not specific to asthma. You may see elevated levels in conditions such as chronic obstructive pulmonary disease (COPD), pneumonia, or upper airway problems, including chronic rhinosinusitis.
These diseases can also involve airway inflammation, which raises nitric oxide. In COPD, FeNO may help identify patients with overlapping asthma features, but it cannot replace standard lung function testing.
Infections that affect airflow, including pneumonia or viral bronchitis, may also cause temporary increases. FeNO should be used in conjunction with other diagnostic tools.
Asthma is a condition that often requires more than one tool for proper diagnosis and ongoing management. While traditional tests like spirometry measure airflow, the FeNO test adds a vital layer by detecting airway inflammation directly. This distinction allows doctors to identify asthma phenotypes, fine-tune treatment with inhaled corticosteroids, and even predict flare-ups before symptoms become severe. At Gwinnett Pulmonary & Sleep, FeNO testing is integrated into a comprehensive care plan that prioritizes both accuracy and personalization. With quick results and noninvasive testing, patients gain clarity about their condition and confidence in their treatment plan.
If you want a more accurate assessment of your asthma and treatment response, book an appointment with Gwinnett Pulmonary & Sleep today and take control of your breathing health.
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