FeNO testing offers a non-invasive approach to understanding respiratory health. It provides insights into airway inflammation, a common factor in various lung conditions. This helps individuals gain a clearer picture of their lung health and potential treatment pathways.
What is a FeNO Test?
A FeNO test measures fractional exhaled nitric oxide (FeNO) in a person’s breath. Nitric oxide is a gas naturally produced in the body, including within the airways of the lungs. When the airways become inflamed, certain cells produce higher levels of nitric oxide.
This test serves as a biomarker, indicating the degree of inflammation present in the airways. Elevated levels of exhaled nitric oxide are particularly associated with a specific type of inflammation called eosinophilic inflammation, which is often seen in conditions like asthma. The FeNO test is a simple and non-invasive procedure.
Why and How a FeNO Test is Performed
FeNO tests are primarily used to help diagnose and manage inflammatory airway diseases, particularly asthma. The measurement of exhaled nitric oxide helps healthcare providers assess the level of eosinophilic inflammation, which is a type of inflammation responsive to corticosteroid medications. This information assists in making informed decisions about starting or adjusting treatment, such as inhaled corticosteroids. Monitoring FeNO levels can also indicate how well a current asthma treatment plan is working over time.
The procedure for a FeNO test is straightforward. The patient breathes in deeply and then exhales slowly and steadily into a handheld device through a mouthpiece. The device then measures the nitric oxide concentration in the exhaled breath. To ensure accurate results, patients might be advised to avoid strenuous exercise, smoking, hot drinks, caffeine, alcohol, and nitrate-rich foods for a period before the test.
Understanding Your FeNO Test Results
FeNO test results are measured in parts per billion (ppb). These values indicate the level of airway inflammation. Generally, higher FeNO values suggest more inflammation. However, these results should always be interpreted by a healthcare professional, who will consider them alongside other clinical information.
For adults, a FeNO level below 25 ppb is typically considered low, suggesting that eosinophilic inflammation is less likely. Levels between 25 and 50 ppb are in an intermediate range, indicating that some inflammation might be present, and these results require careful interpretation within the clinical context. A FeNO value above 50 ppb is considered high, strongly suggesting significant airway inflammation, which often responds well to inhaled corticosteroids.
For children aged five and older, the ranges differ slightly. A FeNO level below 20 ppb is considered low. An intermediate range for children falls between 20 and 35 ppb, while levels above 35 ppb are considered high, indicating likely airway inflammation. When monitoring treatment, a significant change in FeNO levels is considered a decrease of at least 20% for values over 50 ppb, or a decrease of more than 10 ppb for values under 50 ppb. These changes help assess treatment effectiveness and guide adjustments.
Who Benefits from FeNO Testing?
FeNO testing benefits several groups of individuals. People experiencing persistent respiratory symptoms, such as coughing, wheezing, or shortness of breath, who do not yet have a clear diagnosis, may benefit from this test. It can help determine if airway inflammation is contributing to their symptoms.
For individuals already diagnosed with asthma, FeNO testing offers a valuable tool for ongoing management. It can help assess how well their current treatment plan is controlling inflammation and guide decisions on adjusting medication dosages. The test is also useful in differentiating between various types of asthma, such as allergic or eosinophilic asthma, which can influence treatment choices. Furthermore, FeNO testing can assist in distinguishing asthma from other respiratory conditions that present with similar symptoms, like chronic obstructive pulmonary disease (COPD).