What is the initial management for a patient with eosinophilia, elevated Red Cell Distribution Width (RDW), and high Mean Platelet Volume (MPV)?

Initial Management for Eosinophilia with Elevated RDW and High MPV

The initial management for a patient with eosinophilia, elevated RDW, and high MPV should include a complete blood count with differential, peripheral blood smear, comprehensive metabolic panel, and parasite-specific testing based on geographical exposure, followed by empirical treatment with albendazole 400 mg twice daily for 3 days if investigations are negative. 1

Definition and Classification

• Eosinophilia is defined as peripheral blood eosinophil count >0.5 × 10⁹/L
• Severity classification 1:
  • Mild: >0.5 × 10⁹/L
  • Moderate: >1.5 × 10⁹/L
  • Severe: >5.0 × 10⁹/L

Initial Laboratory Evaluation

1. Essential initial tests:

   • Complete blood count with differential (to confirm eosinophilia)
   • Peripheral blood smear (to evaluate blood cell morphology)
   • Comprehensive metabolic panel with liver function tests
   • Urinalysis with protein-to-creatinine ratio
   • C-reactive protein
   • Serum tryptase (to evaluate mast cell activation)
   • Vitamin B12 levels 1

2. Parasite-specific testing:

   • Concentrated stool microscopy (3 samples) 2
   • Serological tests based on geographical exposure
   • Strongyloides serology 1

Clinical History Assessment

Focus on obtaining information about:

• Travel to tropical/subtropical areas
• Exposure to freshwater (risk for schistosomiasis)
• Consumption of raw foods
• Walking barefoot
• Current and recent medications
• Allergy history 1

Specialized Testing Based on Initial Findings

• If persistent unexplained eosinophilia: bone marrow aspirate and biopsy with cytogenetics 1
• If eosinophil count >1500 cells/μL: evaluate for hypereosinophilic syndrome 1
• When GERD vs. eosinophilic esophagitis is suspected: intraesophageal pH monitoring or upper endoscopy after 6-8 weeks of high-dose PPI treatment 2
• For dysphagia: upper GI contrast study to identify strictures 2

Treatment Algorithm

1. If parasitic infection identified:

   • Hookworm: Albendazole 400 mg daily for 3 days
   • Schistosomiasis (Katayama syndrome): Praziquantel 40 mg/kg as single dose, repeated at 6-8 weeks 2, 1
   • Strongyloides: Ivermectin 200 μg/kg/day for 1-2 days
   • Filariasis: Consult specialist for diethylcarbamazine 1

2. If drug-induced eosinophilia suspected:

   • Immediate withdrawal of the causative medication 1

3. If investigations negative:

   • Empirical treatment with albendazole 400 mg twice daily for 3 days 2, 1
   • Consider adding ivermectin 200 μg/kg (exclude Loa loa first if travel to endemic regions) 1

4. For persistent eosinophilia after initial treatment:

   • Evaluate for end-organ damage (cardiac, pulmonary, neurological)
   • Consider hematology or allergy/immunology consultation
   • For hypereosinophilic syndrome: corticosteroids as first-line therapy 1

Monitoring and Follow-up

• Monitor complete blood counts until resolution
• For mild and transient eosinophilia: regular follow-up to confirm resolution
• For persistent eosinophilia: regular monitoring for end-organ damage
• Prompt treatment is crucial to prevent irreversible organ damage, particularly cardiac complications 1

Important Considerations

• Elevated RDW and high MPV may indicate underlying hematologic disorders or inflammatory conditions
• When evaluating for eosinophilic esophagitis, withdraw proton pump inhibitors for at least three weeks prior to endoscopy and biopsy 1
• Consider histological remission when eosinophil count <15 eosinophils/0.3 mm² 1

Common Pitfalls to Avoid

• Failing to exclude secondary causes before diagnosing primary eosinophilia
• Not testing for parasitic infections in patients with travel history
• Delaying treatment in patients with hypereosinophilia (>1500/mm³), which can lead to irreversible organ damage
• Administering ivermectin without excluding Loa loa in people who have traveled to endemic regions 1