Assessment of eosinophilia

Last reviewed: March 2019

Last updated: August 2018

Summary

Eosinophilia is defined as an increase in the peripheral blood eosinophil count. The upper limit of normal is usually taken as about 0.6 × 10⁹/L (600/microlitre), but it is lower (about 0.4 × 10⁹/L [400/microlitre]) if people with minor allergies are excluded. There is no ethnic variation in the normal eosinophil count and no physiological cause of an increased count. [1]

Causes of eosinophilia

The most common causes of eosinophilia depend on socioeconomic and geographical factors. In the developing world the most common cause is parasitic infection (and parasitic infections result in the greatest number of cases worldwide), whereas in the developed world it is allergy. Uncommon and rare causes are important because eosinophilia may be the result of a serious underlying condition.

Hypereosinophilia

The terms eosinophilia and hypereosinophilia do not have any precise definition. Nevertheless, the higher the eosinophil count, the more urgent it is to determine the cause, first because the underlying disease may need treatment in its own right, and second because hypereosinophilia can lead to tissue damage, which can be life-threatening. If eosinophils are extensively degranulated, tissue damage is more likely because of the enzymes, cytotoxic proteins, and cytokines released.

Investigation of eosinophilia

Investigation of eosinophilia should follow the traditional model of clinical history, physical examination, and laboratory and other investigations, taking into account the likely causes in the individual patient.

Differentials

Common

Ascariasis
Strongyloidiasis
Schistosomiasis
Trichinellosis
Urticaria
Pemphigus
Bullous pemphigoid
Asthma
Eczema
Allergic rhinitis

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Uncommon

Clonorchiasis
Fascioliasis
Fasciolopsiasis
Opisthorchiasis
Filariasis
Gnathostomiasis
Toxocariasis
Paragonimiasis
Ancylostoma caninum infestation
Coccidioidomycosis
Herpes gestationis
Drug hypersensitivity
Allergic bronchopulmonary aspergillosis
Eosinophilic granulomatosis with polyangiitis
Eosinophilic oesophagitis
Eosinophilic gastroenteritis
Eosinophilic cellulitis (Wells syndrome)
Chronic eosinophilic leukaemia
Other leukaemias
Non-Hodgkin's lymphoma
Hodgkin's lymphoma
Non-haematological malignancy-associated hypereosinophilia
Lymphocytic variant of hypereosinophilic syndrome
Idiopathic hypereosinophilic syndrome
Wiskott-Aldrich syndrome
Job's syndrome
Hyperimmunoglobulin E syndrome
Severe combined immune deficiency due to adenosine deaminase deficiency
Omenn's syndrome
immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome
Autoimmune lymphoproliferative syndrome (ALPS)
Loeys-Dietz syndrome
Comel-Netherton syndrome
Severe dermatitis, multiple allergies, and metabolic wasting (SAM) syndrome
Muscular sarcocystosis
Cystoisospora belli (formerly Isospora belli) infection
Anisakiasis
Loiasis

Full details

Contributors

Authors VIEW ALL 

Barbara J. Bain, MBBS, FRACP, FRCPath

Professor of Diagnostic Haematology

St Mary's Hospital Campus

Imperial College London

London

Disclosures

BJB is an author of a number of references cited in this topic.

James Uprichard, MBBS, BSc, PhD, FRCP, FRCPath

Consultant Haematologist

Department of Haematology

St George's University Hospitals NHS Foundation Trust

London

Disclosures

JU is on Bayer, Vifor Pharma and Octapharma scientific advisory boards; Bayer, Octapharma, Shire, Vifor Pharma and Daiichi-Sankyo speaker bureaus; is involved in clinical trials associated with Portola, Bayer, Boehringer-Ingelheim and Daiichi-Sankyo; and has received travel support from Bayer.

Peer reviewers VIEW ALL 

Jonathan Bernstein, MD

Professor of Medicine

Department of Internal Medicine

Division of Immunology/Allergy Section

University of Cincinnati

Cincinnati

Disclosures

JB is the editor of the Joint Task Force Practice Parameters on Urticaria.

Jan Cools, PhD

Associate Professor

Department of Molecular and Developmental Genetics

Katholieke Universiteit Leuven

Leuven

Belgium

Disclosures

JC is an author of a reference cited in this topic.

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Assessment of eosinophilia

Summary

Causes of eosinophilia

Hypereosinophilia

Investigation of eosinophilia

Differentials

Common

Uncommon

Contributors

Authors VIEW ALL 

Barbara J. Bain, MBBS, FRACP, FRCPath

Disclosures

James Uprichard, MBBS, BSc, PhD, FRCP, FRCPath

Disclosures

Peer reviewers VIEW ALL 

Jonathan Bernstein, MD

Disclosures

Jan Cools, PhD

Disclosures

Guidelines

Patient leaflets

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