What is the cause of elevated absolute eosinophils (eosinophilia) in a patient?

Elevated Absolute Eosinophils: Diagnostic Approach

Your absolute eosinophil count of 1271 cells/μL represents mild eosinophilia that most commonly results from allergic disorders, parasitic infections, or medication reactions, and requires systematic evaluation based on your travel history, medication use, and symptoms. 1

Understanding Your Eosinophil Level

Your absolute eosinophil count falls into the mild eosinophilia category (500-1500 cells/μL), which is most frequently caused by:

• Allergic conditions including asthma, allergic rhinitis, atopic dermatitis, or chronic cough (up to 40% of chronic cough cases show eosinophilia) 1
• Parasitic infections particularly if you have traveled to endemic regions (accounting for 19-80% of cases in returning travelers) 1
• Medication reactions to various drugs 2

Critical Questions to Guide Diagnosis

Travel History Assessment

• Any travel to tropical or subtropical regions? Fresh water exposure in Africa or tropical areas raises concern for schistosomiasis; consumption of raw or undercooked meat suggests possible helminth infection 1
• Timing matters: The onset of eosinophilia relative to travel helps narrow differential diagnosis 3

Medication Review

• Review all medications started within the past several months, as drug hypersensitivity commonly causes mild eosinophilia 4

Symptom Screening for Organ Involvement

While your level is mild, screen for:

• Respiratory symptoms: Persistent cough, wheezing, or shortness of breath (suggests asthma, eosinophilic pneumonia, or tropical pulmonary eosinophilia) 1
• Gastrointestinal symptoms: Dysphagia or food impaction (warrants endoscopy for eosinophilic esophagitis) 1
• Skin manifestations: Urticaria, pruritic rash, or dermatitis 3
• Cardiac symptoms: Chest pain, dyspnea, or palpitations (rare at this level but critical to exclude) 1

Recommended Diagnostic Workup

First-Line Testing

• Stool examination: Three separate concentrated specimens for ova and parasites if any travel history to endemic areas 1
• Strongyloides serology: Essential in travelers, as this parasite can persist lifelong and cause fatal hyperinfection syndrome in immunocompromised patients 1
• Schistosomiasis serology: If fresh water exposure in endemic regions 1

Additional Considerations

• Allergy evaluation: Consider testing for common allergens if respiratory or skin symptoms present 2
• Chest X-ray: If any respiratory symptoms to identify pulmonary infiltrates 1

When to Escalate Concern

Your current level does not require urgent hematology referral unless:

• Eosinophilia persists >3 months after excluding and treating infectious causes 1
• Count rises to ≥1500 cells/μL (moderate-to-severe range) 1
• Any symptoms suggesting organ damage develop 1

Common Pitfalls to Avoid

• Do not assume normal eosinophil counts exclude parasitic infection - many helminth-infected patients have normal counts, so if travel history is significant, test regardless 1
• Do not rely solely on peripheral eosinophil counts for tissue eosinophilia - conditions like eosinophilic esophagitis require tissue biopsy for diagnosis, as only 10-50% of adults show peripheral eosinophilia 1
• Do not delay parasitic workup in travelers - empiric treatment may be warranted while awaiting results in symptomatic patients 1

Most Likely Scenario

Given your mild elevation without other abnormal blood counts, the most probable causes are:

1. Allergic disorder (asthma, rhinitis, dermatitis) - most common in non-travelers 1
2. Medication reaction - review recent medication changes 2
3. Parasitic infection - if any travel to endemic areas 1

Next step: Discuss with your physician about travel history, current medications, and any symptoms to guide appropriate testing. If you have traveled to tropical regions, parasitic screening should be performed immediately. 1