What is the appropriate management for elevated eosinophils (eosinophilia)?

Management of Elevated Eosinophils (Eosinophilia)

The appropriate management of eosinophilia requires identification of the underlying cause, with treatment directed at the specific etiology while monitoring for organ damage, as persistent eosinophilia >1.5 x 10^9/L requires aggressive intervention to prevent end-organ complications. 1

Diagnostic Approach

Definition and Classification

• Eosinophilia: Absolute eosinophil count (AEC) >500 cells/μL
• Hypereosinophilia: AEC ≥1,500 cells/μL 1
• Classification:
  • Hereditary (familial)
  • Primary (clonal/neoplastic)
  • Secondary (reactive) - most common
  • Undetermined significance 1

Initial Evaluation

1. Confirm eosinophilia with complete blood count and peripheral smear

2. Assess for organ damage with:

   • Comprehensive metabolic panel with liver function tests
   • Urinalysis with protein-to-creatinine ratio
   • C-reactive protein
   • Serum tryptase
   • Vitamin B12 levels 1

3. Key history elements:

   • Travel history (tropical/subtropical areas)
   • Exposure to freshwater
   • Raw food consumption
   • Medication history (current and recent)
   • Allergy history 1

Treatment Algorithm Based on Etiology

1. Secondary (Reactive) Causes - Most Common

Allergic Disorders (80% of cases) 1

• Eosinophilic Esophagitis:
  • Topical steroids: fluticasone 440-880 mg twice daily (adults) or budesonide 2 mg daily 1
  • Proton pump inhibitors as first-line therapy 2
  • Maintenance treatment recommended after clinical remission 2

Parasitic Infections

• Strongyloidiasis: ivermectin 200 μg/kg/day for 1-2 days
• Toxocariasis: albendazole 400mg twice daily for 5 days
• Schistosomiasis: praziquantel 40 mg/kg twice daily for 5 days
• Other helminth infections: specific antiparasitic therapy based on identified organism 1

Drug Reactions

• Discontinue suspected medication
• Consider short course of corticosteroids for symptomatic relief 1

2. Primary (Clonal/Neoplastic) Causes

Hypereosinophilic Syndrome (HES)

• First-line: Prednisolone 30-60 mg/day 1
• Refractory cases:
  • Biologic agents: anti-IL-5 therapies (mepolizumab) or anti-IL-5 receptor antibodies (benralizumab) 1
  • Hydroxyurea or interferon-alpha for steroid-refractory cases 3

Myeloid/Lymphoid Neoplasms with Eosinophilia

• PDGFRA/PDGFRB rearrangements: Imatinib (highly effective) 3
• Other tyrosine kinase fusion genes: Targeted therapy based on specific genetic abnormality 1

3. Eosinophilic Granulomatosis with Polyangiitis (EGPA)

• First-line: Corticosteroids 4, 5
• Severe disease: Add immunosuppressants
• Refractory disease: Consider rituximab or anti-IL-5 therapy (mepolizumab) 4

Monitoring and Follow-up

• Regular monitoring of eosinophil counts
• Vigilance for end-organ damage, particularly cardiac complications
• For patients with mild eosinophilia (<1,500/mm³) without symptoms or signs of organ involvement, a watch-and-wait approach with close follow-up may be appropriate 3
• Repeat endoscopy for assessment if symptoms recur in eosinophilic esophagitis 2

Special Considerations

• Refractory eosinophilia: Consider bone marrow examination to rule out hematologic malignancy 1
• Strictures in eosinophilic esophagitis: Endoscopic dilatation is effective and safe, best combined with anti-inflammatory therapy 2
• Persistent symptoms despite treatment: Consider oesophageal physiological testing in eosinophilic esophagitis 2
• Concomitant atopic disease: Joint management by gastroenterologist and allergist recommended for eosinophilic esophagitis 2

Treatment Pitfalls to Avoid

• Do not use immunomodulators (azathioprine, 6-mercaptopurine) for eosinophilic esophagitis 2
• Do not use anti-TNF or anti-integrin therapies for eosinophilic esophagitis 2
• Do not use sodium cromoglycate, montelukast, or antihistamines as primary treatment for eosinophilic esophagitis (may have role in concomitant atopic disease) 2
• Do not delay treatment in hypereosinophilia (≥1,500/mm³) as this can lead to irreversible organ damage 1, 3