Hypereosinophilia or an elevated eosinophil count can have multiple causes. The differential list includes asthma, atopic disease, drug hypersensitivity, parasitic infections, connective tissue disorders, malignancy (cancer) and rare hypereosinophilic disorders. Hypereosinophilia is defined a blood eosinophil count greater than 1500 per microliter of blood and end organ damage attributable to eosinophilia. A count of greater than 500 eosinophils is generally considered eosinophilia.
A recent study published in The Journal of Allergy and Clinical Immunology: In Practice, looked into over 300 subjects with hypereosinophilia. The study excluded secondary causes of hypereosinophilia (which were primary immunodeficiency in children) and looked into only the primary causes. Hypereosinophilia is most common in adults aged 20-50 years and has been reported in children as young as 1 year old. The underlying cause is often difficult to determine. Besides the main primary causes of asthma, atopic disease, drug allergy, parasitic infections, connective tissue disease and cancer other secondary causes are helminth (worm) infections (Toxocara, strongyloidiasis and onchocerciasis).
The majority of subjects with hypereosinophilia received corticosteroids at some time during their management. Other medications commonly prescribed in study subjects were hydroxyurea, interferon-alpha, imatinib and methotrexate. Anti-IL-5 antibody, Nucala and Cinqair was administered to some subjects who were involved in a treatment protocol.
Children or adults with hypereosinophilia can have gastrointestinal manifestations including, abdominal pain, nausea/vomiting, diarrhea; dermatologic manifestations including rash, urticaria, angioedema; allergic manifestations including asthma, allergic rhinitis or sinusitis; hematologic manifestations included thrombus, splenomegaly, lymphadenopathy, neoplasm; constitutional manifestations included infiltrates identified with imaging and pleural effusions’ rheumatologic manifestations including myalgia/arthralgia and eosinophilic fasciitis; neurologic manifestations included clinical history of stroke or neuropathy; cardiac manifestations included valvular disease, endomyocardial fibrosis, pericarditisis and elevated troponin.
If you have had a CBC done and there is an elevated eosinophil count speak to your doctor about the possible causes of it. Hypereosinophilia is a rare disorder but having elevated eosinophil levels can be a marker for allergy diseases most commonly.
A recent study published in March 2021 of the Annals of Allergy titled “Characterization of hypereosinophilia in university health care systems”, looked at the major etiologies. Hypereosinophilia (HE) is defined as peripheral blood eosinophilia greater than or equal to 1500 cells/uL.
- Hypereosinophilic syndrome (HES) 12%
- Malignancy 11%
- drug-induced diseases 10%
- gastrointestinal diseases including eosinophilic esophagitits and eosinophilic gastrointestinal disease 7%
- Despite workups by doctors, 46% were deemed idiopathic
- Other causes found were; eosinophilic granulomatosis with polyangiitis, infection (Strongyloides), Graft-versus-host disease, chronic eosinophilic pneumonia, severe eosinophilic asthma, allergic bronchopulmonary apergillosis, Gleich’s syndrome, eosinophilia-myalgia syndrome, eosinophilic fasciitis.