What is the appropriate workup and management for a patient with a differential leukocyte count (DLC) showing eosinophils at 54%?

Workup for DLC Eosinophils 54%

Immediate Assessment Required

A differential eosinophil count of 54% represents severe hypereosinophilia requiring urgent evaluation for end-organ damage and immediate identification of the underlying cause, with particular attention to helminth infections, drug reactions, and eosinophil-mediated organ injury. 1

This level of eosinophilia (assuming normal total WBC, this translates to absolute eosinophil count well above 1.5 × 10⁹/L) carries significant risk of morbidity and mortality and demands systematic evaluation. 1

Critical Red Flags to Assess Immediately

Evaluate urgently for symptoms suggesting end-organ damage: 1

• Cardiac involvement: Chest pain, dyspnea, heart failure symptoms, arrhythmias, or palpitations 1
• Pulmonary involvement: Persistent cough, wheezing, dyspnea, or infiltrates on imaging 1, 2
• Neurological involvement: Altered mental status, focal neurologic deficits, or peripheral neuropathy 1
• Gastrointestinal involvement: Dysphagia, food impaction, abdominal pain, or diarrhea 1, 3

Essential History Components

Travel and Exposure History

• Detailed travel history: Fresh water exposure in Africa/tropical regions, timing relative to eosinophilia onset 1
• Dietary exposures: Raw or undercooked meat consumption 1
• Geographic risk: Helminth infections account for 19-80% of eosinophilia cases in returning travelers or migrants 1

Medication Review

• Review all medications, as drug reactions are a common cause of eosinophilia in non-endemic areas 1, 3

Symptom Assessment

• Respiratory symptoms: Asthma, chronic cough, wheezing 4, 2
• GI symptoms: Dysphagia, food impaction, reflux 4, 3
• Allergic history: Atopic dermatitis, allergic rhinitis 3

Mandatory Initial Laboratory Workup

Parasitic Evaluation (First Priority)

• Stool microscopy: Three separate concentrated specimens for ova and parasites 1, 3
• Strongyloides serology and culture: Critical due to risk of fatal hyperinfection syndrome in immunocompromised patients 1
• Schistosomiasis serology: If fresh water exposure in endemic areas 1
• Additional serology: Based on specific travel exposures 1

Critical Warning: If Loa loa is suspected (travel to Central/West Africa), do NOT use diethylcarbamazine if microfilariae are seen on blood film—this may cause fatal encephalopathy. Use corticosteroids with albendazole first to reduce microfilarial load to <1000/ml before definitive treatment. 1

Additional Laboratory Tests

• Complete blood count with absolute eosinophil count calculation 1
• Serum IgE levels (often elevated in eosinophilic conditions) 2
• ANCA testing to exclude vasculitis 4, 2
• Serum IgG4 concentration (may correlate with disease activity in EGPA) 4

Organ Damage Assessment

Given the severity of eosinophilia, systematic evaluation for end-organ damage is mandatory: 1

Cardiac Evaluation

• Electrocardiogram 1
• Cardiac troponin and NT-proBNP measurement 1
• Echocardiography: If troponin elevated or clinical features suggest cardiac injury 1
• Cardiac MRI: When elevated troponin or clinical cardiac features present 1

Pulmonary Evaluation

• Chest X-ray: Identify pulmonary infiltrates 1, 2
• High-resolution CT chest: Look for peripheral infiltrates, ground glass opacities, nodules 2
• Pulmonary function tests: If respiratory symptoms present 1
• Bronchoscopy with BAL: If imaging suggests parenchymal disease; >25% eosinophils on BAL confirms eosinophilic pneumonia 2

Neurologic Evaluation

• Electromyography: If sensory or motor deficits present 1
• Nerve biopsy: If EMG consistent with neuropathy 1

Gastrointestinal Evaluation

• Endoscopy with multiple biopsies: If dysphagia or food impaction present (six biopsies from at least two sites) 4, 3
• Eosinophilic esophagitis diagnosis requires >15 eosinophils per 0.3 mm² in tissue 3
• Note: Peripheral eosinophilia occurs in only 10-50% of adults with eosinophilic esophagitis 1, 3

Specialist Referral Indications

• Hematology referral: If eosinophilia persists >3 months after infectious causes excluded or treated 1
• Gastroenterology: If GI symptoms or suspected eosinophilic GI disease 3
• Pulmonology: If pulmonary infiltrates or respiratory symptoms 2
• Cardiology: If any cardiac biomarker elevation or symptoms 1
• Infectious disease: For complex parasitic infections or immunocompromised patients 1

Common Pitfalls to Avoid

• Do not assume normal eosinophil counts exclude helminth infection: Many infected patients have normal counts 1
• Do not wait for symptoms before investigating: End-organ damage can be subclinical initially 1
• Do not rely solely on peripheral eosinophil counts for tissue eosinophilia: Tissue biopsy is the gold standard for conditions like eosinophilic esophagitis 1, 3
• Do not overlook Strongyloides: Can persist lifelong and cause fatal hyperinfection in immunocompromised patients 1

Initial Management Considerations

While awaiting workup results:

• Empiric antiparasitic therapy may be considered in returning travelers with asymptomatic eosinophilia: Albendazole 400 mg single dose plus ivermectin 200 μg/kg single dose 3
• Corticosteroids: Reserved for confirmed eosinophilic pneumonia or other specific diagnoses after excluding parasitic infections 2, 5
• Avoid premature corticosteroid use: May worsen Strongyloides hyperinfection 1