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Eosinophilia

 

This guideline applies to adults

 

Introduction

The common causes of eosinophilia are allergy (asthma, eczema, seasonal allergies) and medication. In the context of symptoms suggestive of asthma a raised eosinophilia count is now diagnostic – please refer to guidelines  - Asthma

Persistently raised eosinophils may be toxic, especially at levels above 1.5 x 109/l.

Consider intestinal/other parasitic causes if suggested by travel, environmental or occupational history, even if long ago.

A more extensive list of causes can be found here - British Journal of Haematology | Wiley Online Library

 

In scope:

  • Raised eosinophil count (>0.5x109/l) on FBC

 

Not in scope:

  • All other forms of blood disorders.


  

Red Flag Features

  • ‘B’ Symptoms - eg night sweats, unintentional weight loss, pruritus
     
  • Blood film consistent with malignancy
     
  • New onset cardiac or pulmonary problems – seek early advice.

*This list is non exhaustive 



 

Investigations required prior to referral

In patients who are otherwise well with mild to moderate eosinophilia (between 0·5 and 1·5x109/l) further testing may not be indicated, especially if there is a history of asthma, atopy or allergy.

Patients with systemic symptoms or persistent eosinophilia (>1.5x109 for 8 weeks or longer) should be investigated for possible secondary causes -

  • FBC and blood film
     
  • U&E, LFT, Bone, LDH, CRP, vitamin B12 assay
     
  • Consider stool sample to check for parasites
     
  • Consider CXR if cardiac / pulmonary symptoms.


 

Management optimisation

  • Consider potential medication causes and review the need for ongoing use as appropriate Drug-induced eosinophilia – GPnotebook

  • If history is suggestive of asthma, eczema or allergy refer to appropriate guidelines for further management
     
  • Investigate and treat any other associated underlying systemic symptoms as appropriate.

 

 

Advice and Guidance

Haematology A&G can be accessed via ERS: Haematology Advice & Guidance

This service should not be used for suspected fast track referrals.



 

Referral

Emergency and red flags

 

Urgent referral criteria

  • Have a lower threshold for urgent referral if there are associated new onset cardiac or pulmonary symptoms. Depending on clinical impression and site of pathology consider urgent referral to other secondary care specialty eg respiratory or cardiology.

 

Routine referral criteria

Refer routinely to haematology if eosinophil count >1.5x109 persistent for 8 weeks or more

and

  • Systemic symptoms

or

  • No detectable secondary cause.

If evidence of end organ damage (eg unexplained cardiac failure symptoms or deteriorating respiratory function)refer to appropriate secondary care specialty according to clinical impression and site of pathology.

 

Referral instructions

Please give details of -

  • Any history of allergic disorders or skin rashes
  • Any thrombotic history
  • Travel history
  • Medication history including accurate start dates, and time correlation with blood counts
  • Any cardiorespiratory, gastrointestinal or constitutional symptoms
  • Examination findings including signs of allergy, skin rash, cardiac and respiratory systems, lymph nodes / hepatosplenomegaly.


 

Supporting Information

For professionals

 

References

Page Review Information

Review date:

24 June 2025

Next review date:

24 June 2027

Clinical editor:

Dr Laura Lomas

Contributors:  

Haematology Site-Specific Group (SSG), Peninsular Cancer Alliance

                              

Dr Michelle Furtado