American Board of Internal Medicine (ABIM) Certification Practice Exam

What laboratory findings are typically associated with allergic bronchopulmonary aspergillosis?

1. Low serum IgE levels

2. Serum IgE levels greater than 1000 U/mL

3. Negative skin tests for allergens

4. Presence of specific IgG antibodies to dust mites

The correct answer is: Serum IgE levels greater than 1000 U/mL

Allergic bronchopulmonary aspergillosis (ABPA) is an immune-mediated hypersensitivity reaction to the fungus Aspergillus species, primarily affecting individuals with underlying respiratory conditions like asthma or cystic fibrosis. One key laboratory finding associated with ABPA is significantly elevated serum IgE levels, often exceeding 1000 U/mL. This increase in IgE is indicative of the body's allergic response to Aspergillus antigens. Elevated IgE levels are commonly found in allergic conditions, reflecting a Th2-mediated immune response, which is characteristic of reactions to environmental allergens, including fungi. In contrast, low serum IgE levels would not align with the presentation of ABPA, as such levels typically reflect a lack of allergic sensitization. Similarly, negative skin tests for allergens would suggest a lack of specific allergic responses, which is inconsistent with the diagnosis of ABPA. The presence of specific IgG antibodies to dust mites is unrelated to ABPA, as this condition specifically involves a response to Aspergillus, not general environmental allergens like dust mites. Overall, the hallmark of allergic bronchopulmonary aspergillosis is a significant rise in serum IgE levels, affirming the diagnosis and illustrating the immune system's reactive nature to