What does an eosinophil (white blood cell) percentage of 11.8% indicate?

From the Guidelines

An eosinophil percentage of 11.8% is not directly indicative of eosinophilic oesophagitis (EoE) as the diagnosis of EoE requires a combination of clinical, endoscopic, and histological features, including an eosinophil count of >15 eosinophils per 0.3 mm2 in any biopsy specimen 1.

Understanding Eosinophil Percentage

Eosinophil percentage is a measure that can indicate various conditions, but in the context of eosinophilic oesophagitis, the focus is on the absolute eosinophil count per high power field (hpf) rather than the percentage.

• The normal range for eosinophil percentage in blood tests is typically considered to be 0-6% of total white blood cells, but this can vary slightly by laboratory.
• An elevated eosinophil percentage, such as 11.8%, suggests eosinophilia, which can be associated with several conditions including allergic reactions, parasitic infections, autoimmune disorders, or medication reactions.

Diagnosis of Eosinophilic Oesophagitis

The diagnosis of EoE is based on a combination of clinical symptoms (such as dysphagia, food impaction, and abdominal pain), endoscopic findings (like esophageal rings, furrows, and white exudates), and histological evidence of eosinophilic infiltration 1.

• Histologically, a diagnosis of EoE is supported by an eosinophil count of >15 eosinophils per 0.3 mm2 in any biopsy specimen, along with other features such as basal cell hyperplasia, eosinophil microabscesses, and subepithelial sclerosis 1.
• The percentage of eosinophils in the blood or tissue does not directly correlate with the diagnosis of EoE; instead, the absolute count of eosinophils per high power field is crucial.

Clinical Implications

Given the information provided, an eosinophil percentage of 11.8% would prompt further investigation to determine the underlying cause of eosinophilia, which could include:

• Complete blood count with differential to assess the absolute eosinophil count.
• Stool examination for parasites.
• Allergy testing.
• Endoscopy with biopsies if EoE is suspected, based on clinical presentation and other diagnostic criteria. It's essential to consult with a healthcare provider for a comprehensive evaluation and appropriate management based on the underlying cause of the elevated eosinophil percentage.

From the Research

Eosinophil Percentage

• An eosinophil percentage of 11.8% is considered elevated, as the normal range for eosinophils is typically between 1-4% of the total white blood cell count 2.
• Eosinophilia, which is defined as an elevation of eosinophils in the bloodstream, can be caused by a variety of factors, including parasitic disease, allergic disease, autoimmune disease, and malignant states 2.

Possible Causes

• The causes of eosinophilia can be broadly categorized into primary (clonal) and secondary (reactive) eosinophilia 3.
• Primary eosinophilia includes conditions such as hypereosinophilic syndrome, while secondary eosinophilia can be caused by factors such as parasitic infections, allergic reactions, and autoimmune disorders 3.

Diagnostic Evaluation

• Diagnostic evaluation of eosinophilia typically involves a combination of morphologic review of the blood and marrow, standard cytogenetics, fluorescence in situ hybridization, next-generation sequencing gene assays, and flow immunophenotyping 3.
• The goal of diagnostic evaluation is to identify the underlying cause of eosinophilia and to determine the appropriate course of treatment 3.

Treatment Options

• Treatment options for eosinophilia depend on the underlying cause and may include medications such as corticosteroids, hydroxyurea, and interferon-α 3, 4.
• In some cases, biologic therapies such as mepolizumab and benralizumab may be used to target specific pathways involved in eosinophilia 3, 4.