American Board of Internal Medicine (ABIM) Certification Practice Exam

Which laboratory findings are associated with Churg-Strauss syndrome?

1. Elevated creatinine levels

2. Negative P-ANCA

3. Elevated IgE

4. Decreased eosinophils

The correct answer is: Elevated IgE

Churg-Strauss syndrome, also known as eosinophilic granulomatosis with polyangiitis, is characterized by a number of clinical features, including asthma, eosinophilia, and systemic vasculitis. One of the hallmark laboratory findings associated with this condition is an elevated level of immunoglobulin E (IgE). In patients with Churg-Strauss syndrome, the inflammatory process, particularly the involvement of eosinophils, leads to increased IgE levels. These levels are often reflective of the underlying allergic response and the presence of eosinophilia, which is a significant factor in the pathophysiology of the syndrome. Elevated IgE levels can further indicate the activity of the disease, especially in the context of asthma, which is commonly present in these patients. Other laboratory findings related to this syndrome typically include positive perinuclear antineutrophil cytoplasmic antibodies (P-ANCA), specifically the myeloperoxidase (MPO) type, and eosinophilia, rather than decreased eosinophils. Therefore, the association of elevated IgE levels with Churg-Strauss syndrome provides insight into the immune mechanisms involved in the condition and underscores the immunological underp