What is the appropriate management for eosinophilia?

Management of Elevated Eosinophils (6.8)

The appropriate management for eosinophilia requires a systematic approach to identify and treat the underlying cause, with empirical therapy of albendazole 400 mg plus ivermectin 200 μg/kg as first-line treatment for possible helminth infection in patients with travel history to endemic regions. 1

Diagnostic Evaluation

• Eosinophilia is defined as a peripheral blood eosinophil count greater than 1.5 × 10^9/L (1500/mm^3) 2
• Diagnostic evaluation should focus on distinguishing between:
  • Secondary/reactive causes (most common) 3
  • Primary/clonal disorders (hematologic malignancies) 2

Essential Initial Investigations:

• Travel history to identify potential parasitic infections 1
• Stool studies including concentrated microscopy and PCR for parasites 4
• Evaluation for allergic conditions, connective tissue disorders, and malignancies 5
• For suspected primary eosinophilia: blood and bone marrow morphology, cytogenetics, and molecular testing 2

Treatment Algorithm

Step 1: Treat Parasitic Infections (if suspected)

• For patients with travel history to endemic regions:
  • Empiric treatment with albendazole 400 mg single dose plus ivermectin 200 μg/kg single dose 4
  • For specific parasites:
    • Strongyloidiasis: ivermectin 200 μg/kg daily for 2 days 4
    • Ascariasis/hookworm: albendazole 400 mg as a single dose 4
    • Schistosomiasis: praziquantel 40 mg/kg in two divided doses for 1 day 4

Step 2: For Eosinophilic Esophagitis (if GI symptoms present)

• Proton pump inhibitor therapy twice daily for 8-12 weeks 6
• Topical steroids are effective for inducing histological and clinical remission 6
• Dietary management options:
  • Two-food elimination diet (milk +/- wheat or egg) for 8-12 weeks 6
  • If no response, progress to four-food elimination diet (milk, wheat, egg, soya) 6
  • Six-food elimination diet if previous approaches fail 6

Step 3: For Primary Eosinophilic Disorders

• For milder forms of eosinophilia without organ involvement, a watch and wait approach with close follow-up 2
• For PDGFRA or PDGFRB rearrangements: imatinib (critical to identify these cases) 2
• For idiopathic hypereosinophilic syndrome:
  • First-line: corticosteroids (prednisone) 2
  • Second-line: hydroxyurea or interferon-alpha 2
  • FDA-approved: mepolizumab (IL-5 antagonist) for idiopathic HES 2

Special Considerations

• Endoscopy with biopsy is recommended for patients with suspected eosinophilic esophagitis 6
• At least six biopsies should be taken from different anatomical sites within the esophagus 6
• For patients with eosinophilia and neurological symptoms, exclude parasitic infections of the CNS and consider corticosteroids 6
• Patients with eosinophilia refractory to treatment and/or with significant concomitant atopic disease should be jointly managed by a specialist team 6

Monitoring and Follow-up

• After initiation of therapy, endoscopy with biopsy while on treatment is recommended to assess response in cases of eosinophilic esophagitis 6
• Histological response should be classified according to eosinophil density, with remission defined as <15 eosinophils/0.3 mm^2 6
• Regular monitoring of eosinophil counts is essential to evaluate treatment response 2
• For patients on corticosteroids, monitor for side effects and consider bone and stomach protection measures 6