Raised eosinophils

Eosinophilia is a raised eosinophil count (1,2,3,4)

This occurs where the eosinophil count is greater than 0.44 x 10^9/l (3)

• however has been noted that the normal range for a peripheral blood eosinophil count in healthy individuals is generally defined internationally as 0.05-0.5×10^9/L (4)
  • eosinophilia is a raised number of eosinophils in peripheral blood (>0.5×10^9/L)
  • hypereosinophilia is >=1.5×109/L on two tests separated by at least one month
  • eosinophil count can vary with extremes of age
    • eosinophil levels are higher in neonates than adults and gradually reduce in older people.

It may be a feature of the following conditions:

• asthma and allergic disorders - asthma, hypersensitivity, drugs, angioneurotic oedema
• parasitic infections - especially schistosomiasis, echinococciasis
• polyarteritis nodosa
• Churg-Strauss syndrome
• Addison's disease
• skin disease - pemphigus, urticaria, eczema, dermatitis herpetiformis, erythema multiforme
• malignancy:
  • Hodgkin's disease
  • carcinoma
  • haematological malignancies:
    • chronic myeloid leukaemia
    • other myeloproliferative syndromes
    • eosinophilic leukaemia
• Loeffler's syndrome
• Loeffler's endocarditis
• scarlet fever
• irradiation
• during convalescence from any infection
• hypereosinophilic syndrome
• post-splenectomy
• cholesterol emboli syndrome
• drugs that may cause raised eosinophil count include (1,2,3,4):
  • antimicrobials
    • such as penicillins, cephalosporins, nitrofurantoin, tetracyclines, daptomycin, fluoroquinolones
  • sulphonamides
    • such as sulfasalazine, septrin, dapsone
  • ranitidine
  • allopurinol
  • angiotensin converting enzyme (ACE) inhibitors
  • anticonvulsants
    • such as phenytoin, carbamazepine, lamotrigine
  • antiretrovirals
    • nevirapine, abacavir
  • non-steroidal anti-inflammatory drugs (NSAIDs)
  • methotrexate
  • interleukin-2 (IL-2)

If raised eosinophil count in an adult (3):

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Factors such as intercurrent steroid treatment and bacterial or viral infection can transiently lower eosinophil counts (4)

Reference:

• Felig P et al (2001) Endocrinology and Metabolism. McGraw-Hill.
• Hart FD (Ed) (2005). French's Index of Differential Diagnosis.
• NHS Camden CCG. Abnormal FBC guidance - for adults (Accessed 30/10/19)
• Thakker C, Booth H L, Lambert J, Morgan S, Checkley A M. Investigating eosinophilia BMJ 2023; 380 :e070295 doi:10.1136/bmj-2022-070295