Etiologies and differential markers of eosinophilia-associated diseases in the Allergy Department of a single university hospital

ABSTRACT

PURPOSE: We aimed to analyze the frequency of eosinophilia-associated diseases and to search for possible markers that may be useful for their differential diagnosis. METHODS: We retrospectively reviewed the medical records of 148 patients with peripheral blood eosinophil count of more than 500/µL who visited the Allergy Department of Chonnam National University Hospital for the first time from January to December 2016. Blood eosinophilia was categorized as mild (5,000/µL). RESULTS: Blood eosinophilia was mostly caused by allergic diseases (41.9%), parasitic infestation (23.6%), and drug allergy (19.6%). Eosinophil count was higher in patients with parasitic infestation (P<0.01), drug allergy (P<0.01), hypereosinophilic syndrome (HES, P<0.001), or eosinophilic granulomatosis with polyangiitis (EGPA, P<0.001) than in those with allergic diseases. The eosinophilic cationic protein level was higher in patients with HES than in those with allergic diseases (P<0.05) and parasitic infestation (P<0.05). The total IgE level was lower in patients with HES than in those with parasitic infestation (P<0.05) and EGPA (P<0.05). The vitamin B12 level was higher in patients with HES than in those with parasitic infestation (P<0.05). There was no statistically significant difference in tryptase levels between the groups. The most common cause of mild eosinophilia was allergic diseases (59.8%), followed by parasitic infestation (22.7%) and drug allergy (13.4%). The common causes of moderate eosinophilia were drug allergy (37.8%), parasitic infestation (29.7%), and allergic diseases (10.8%). The common causes of severe eosinophilia were EGPA (28.6%), HES (21.4%), parasitic infestation (14.3%), and drug allergy (14.3%). CONCLUSION: Common causes of blood eosinophilia in patients who visit the allergy department are allergic diseases, parasitic infestation, and drug allergy. Several markers, including eosinophil count, total IgE, and vitamin B12, may be useful for the differential diagnosis of eosinophilia-associated diseases.