American Board of Internal Medicine (ABIM) Certification Practice Exam

In the context of allergic bronchopulmonary aspergillosis (ABPA), what level of eosinophilia is significant?

1. Less than 200 uL

2. Between 200 and 400 uL

3. Over 500 uL

4. Exactly 600 uL

The correct answer is: Over 500 uL

In the context of allergic bronchopulmonary aspergillosis (ABPA), a significant level of eosinophilia is typically characterized by eosinophil counts that are over 500 cells per microliter (uL) of blood. This elevated eosinophil count is a critical component of the diagnostic criteria for ABPA, as it reflects the immune response associated with the exaggerated sensitivity to the allergens produced by the Aspergillus species. Eosinophils play a key role in the pathogenesis of allergic conditions and are indicative of an underlying allergic response, which is characteristic of ABPA. In addition to elevated eosinophilia, the diagnosis of ABPA is supported by other findings such as elevated serum IgE levels and the presence of specific IgE and IgG antibodies against Aspergillus species. Lower levels of eosinophilia, such as counts below 200 uL or even within the range of 200 to 400 uL, may not sufficiently indicate the presence of ABPA or may be seen in other conditions, but they do not meet the threshold typically recognized for significant eosinophilia in this context. This underscores the importance of the over 500 uL threshold in the diagnosis and management of