Neutropenia

Disease Description (Causes and Symptoms)

• Definition summary: Eosinophilia refers to a condition in which eosinophils in peripheral blood (normal absolute count approximately ≤400–500 cells/µL or 3–5% of granulocytes) are increased. It is classified as mild (400–1,500/µL), moderate (1,500–5,000/µL), or severe (>5,000/µL).
• Main causes
  • Parasitic infections (intestinal or tissue larvae, etc.)
  • Allergic diseases (atopic disease, asthma, etc.) and drug-induced reactions (antibiotics, NSAIDs, antipsychotics, etc.)
  • Hematologic and neoplastic diseases (hypereosinophilic syndrome, leukemia, lymphoma)
  • Autoimmune diseases and vasculitis (e.g., eosinophilic vasculitis/EGPA (Churg–Strauss))
  • Endocrine causes (such as adrenal insufficiency), specific fungal infections, genetic causes, etc.
• Pathophysiology (briefly): Increased eosinophil counts and eosinophil activation may cause tissue infiltration, inflammation, and fibrosis. In particular, damage to major organs such as the heart (myocardium and endocardium), lungs, skin, nervous system, liver, and spleen can cause problems.
• Main symptoms
  • Often asymptomatic (discovered during a health checkup)
  • Nonspecific systemic symptoms: fatigue, weight loss, fever, generalized edema
  • Local symptoms: skin itching and rash, cough and shortness of breath (pulmonary infiltration), abdominal pain and vomiting (gastrointestinal), peripheral neuropathy (sensory disturbances and muscle weakness)
  • With cardiac involvement: heart failure, restrictive cardiomyopathy, vascular and valvular damage → may be life-threatening

Treatment Methods

• General principles: First identify the cause → treat the underlying disease
  • If a parasitic infection is suspected: administer an appropriate anthelmintic (selected according to the type of parasite)
  • If drug-induced: discontinue the causative drug and observe the course (generally repeat testing after 1–2 months)
  • Allergic lesions: allergen avoidance and symptomatic treatment (antihistamines, inhaled steroids, etc.)
  • Neoplastic or hematologic causes: anticancer or immunotherapy in the relevant specialty (Hematology and Oncology)
• Idiopathic or severe eosinophilia (visceral involvement or high counts)
  • Corticosteroids (systemic steroids) are the cornerstone of initial treatment (follow the physician’s instructions)
  • In steroid-resistant or recurrent cases: consider cytotoxic agents such as hydroxyurea and vincristine, and use of interferon-alfa
  • Targeted therapy: IL‑5-targeting antibodies (e.g., mepolizumab) are used for specific indications (at the specialist’s discretion)
  • Vasculitis (such as EGPA): steroids + immunosuppressants (e.g., cyclophosphamide) or biologic agents (at the specialist’s discretion)
• Management of complications and organ damage: In cases of cardiac involvement, consultation with a cardiologist (treatment of heart failure and arrhythmias, and mechanical treatment if necessary); appropriate management when there is a risk of thrombosis
• Lifestyle management and precautions
  • Consult a doctor before taking new medications or supplements
  • Avoid exposure and maintain hygiene, including considering travel to areas at risk for parasitic infections and contact with pets
  • Regular blood tests and monitoring of organ function (such as the heart and lungs)

Checklist Before an Outpatient Visit (Items to Bring and Example Questions)

• Items to bring
  • List of current medications and supplements (if possible, medication packets or photographs)
  • Previous test results (recent CBC with differential, chest X‑ray/CT, echocardiography, etc.)
  • Notes recording when recent symptoms began and how they progressed (fever, respiratory, skin, or neurological symptoms, etc.)
  • Information about travel (location and timing for overseas travel), pets, dietary habits, and drinking water
• Information that must be provided during the consultation
  • Recently started medications or supplements and vaccination history
  • Findings suggesting a parasitic infection (abdominal pain, diarrhea, cough, and persistent eosinophil count elevation)
  • Whether chest pain, shortness of breath, persistent fever, or neurological changes (numbness or muscle weakness) have occurred

Examples of General Questions to Ask the Doctor

• "What range is my eosinophil count (absolute count) currently in, and is it at a level that requires treatment?"
• "What is the suspected cause at this time, and what additional tests are needed?"
• "What are the expected effects and possible side effects of the prescribed medication?"
• "What tests (blood tests, echocardiography, etc.) should I have regularly, and how often?"

Examples of Disease-Specific Questions

• "How do you check for possible cardiac involvement? Do I need echocardiography or a cardiac enzyme test?"
• "When a parasitic infection is suspected, which tests (stool tests or serologic tests) are recommended, and how many times should they be performed?"
• "Is the (name of a specific medication) I am taking likely to cause eosinophilia? Should I stop taking it?"

(If necessary, consultation with other departments: Hematology, Allergy and Immunology, Infectious Diseases, Cardiology, Neurology, etc.)