From the Guidelines
Elevated eosinophils, known as eosinophilia, should be investigated to determine the underlying cause, with the most recent guidelines from 2025 1 emphasizing the importance of identifying the cause to guide appropriate treatment and prevent potential organ damage. Eosinophilia is a common finding in various conditions, including allergic reactions, parasitic infections, certain medications, autoimmune disorders, and rarely, hematologic malignancies.
- Common causes of eosinophilia include:
- Allergic reactions
- Parasitic infections
- Certain medications
- Autoimmune disorders
- Hematologic malignancies For mild to moderate elevations (500-1,500 cells/μL) without symptoms, monitoring may be sufficient, as suggested by previous studies 1. However, for higher counts or symptomatic cases, it is essential to address the underlying cause:
- Treat allergies with antihistamines or corticosteroids
- Use appropriate antiparasitic medications for parasitic infections
- Discontinue offending medications
- Manage autoimmune conditions with immunosuppressants Severe eosinophilia (>1,500 cells/μL) may require urgent evaluation to prevent organ damage, as highlighted in the 2020 guidelines for myeloid/lymphoid neoplasms with eosinophilia and TK fusion genes 1. In cases of hypereosinophilic syndrome, systemic corticosteroids like prednisone (40-60mg daily) are typically the first-line treatment. Eosinophils are white blood cells that help fight parasitic infections and participate in allergic responses by releasing inflammatory mediators, and their elevation indicates an immune system activation that requires appropriate investigation and management to prevent potential tissue damage from prolonged eosinophil-mediated inflammation. The diagnostic approach should include a comprehensive evaluation, including laboratory tests such as CBC with differential, comprehensive metabolic panel, serum tryptase levels, and vitamin B12 levels, as well as additional testing based on the patient's history, symptoms, and physical examination findings 1.
From the Research
Definition and Causes of Elevated Eosinophils
- Eosinophilia is defined as an elevation of eosinophils in the bloodstream, typically above 450-550 cell/μL 2.
- There are various reasons for eosinophilia, including parasitic disease, allergic disease, autoimmune, connective tissue disease, rheumatologic disease, primary eosinophilia, and malignant states 2.
Diagnosis and Evaluation
- The workup of a patient with eosinophilia should involve a thorough history and physical examination, followed by histological confirmation whenever possible 3.
- A rational approach to diagnosis includes serologic, blood, and bone marrow cell analyses, genetic testing, and radiologic imaging to distinguish between different causes of eosinophilia 3.
- Input from specialists, such as hematologists, dermatologists, pulmonologists, gastroenterologists, and neurologists, can help narrow down the possibilities and result in a specific diagnosis 3.
Management and Treatment
- The goal of therapy is to mitigate eosinophil-mediated organ damage, and treatment options vary depending on the underlying cause of eosinophilia 4, 5.
- For patients with milder forms of eosinophilia, a watch and wait approach with close follow-up may be undertaken, while those with more severe forms may require treatment with corticosteroids, hydroxyurea, or interferon-α 4, 5.
- Targeted therapies, such as imatinib, mepolizumab, and benralizumab, have shown efficacy in the management of specific eosinophilic disorders, and their use is an active area of investigation 4, 5.
Multidisciplinary Approach
- A multidisciplinary approach to the management of eosinophil-associated inflammatory diseases is essential, involving collaboration between health professionals from different specialties 6.
- This approach allows for personalized treatment and follow-up, taking into account the various multimorbidities that frequently occur in patients with eosinophil-associated diseases 6.