Which diseases are monitored by FEno testing?

FEno testing, which measures fractional exhaled nitric oxide levels, is primarily used to assess airway inflammation and is particularly relevant in the context of respiratory diseases. It is especially useful in the monitoring and management of asthma, as elevated levels of FEno can indicate eosinophilic airway inflammation, which is a hallmark of asthma exacerbations.

In addition to asthma, FEno testing is relevant in assessing conditions like cystic fibrosis, where airway inflammation is common, and chronic obstructive pulmonary disease (COPD), especially in patients whose condition may have an inflammatory component. This makes option B the correct choice, as these diseases involve inflammation of the airways where FEno testing provides valuable insights into the effectiveness of anti-inflammatory therapies and overall disease control.

In contrast, the other options pertain to systemic conditions that do not have a direct correlation with airway inflammation or are assessed through different diagnostic methods rather than through FEno testing.