Professional and Linguistic Assessments Board (PLAB) Practice Exam

Which diagnostic test is used for confirming Asthma?

1. Pulmonary function test

2. Fractional exhaled nitric oxide (FeNO)

3. CT scan of the chest

4. Chest X-ray

The correct answer is: Fractional exhaled nitric oxide (FeNO)

The fractional exhaled nitric oxide (FeNO) test is significant in confirming asthma as it measures the level of nitric oxide in the breath, which is often elevated in individuals with asthma due to inflammation in the airways. This test provides a non-invasive way to assess airway inflammation and can help differentiate asthma from other respiratory conditions. In the context of asthma, elevated levels of FeNO correlate with eosinophilic inflammation, a common characteristic of asthmatic patients. While pulmonary function tests are important for assessing lung function and can indicate airflow obstruction characteristic of asthma, they do not specifically confirm the diagnosis. CT scans and chest X-rays are primarily used to evaluate structural lung issues or exclude other conditions, rather than to confirm asthma itself. While they can provide valuable information, they do not directly assess airway inflammation or airway hyperreactivity, which is central to the diagnosis of asthma. Thus, FeNO serves as a key tool in confirming asthma by directly measuring the inflammatory response in the airways, making it a valuable component in the diagnostic process.