What should be done for a patient with eosinopenia (low eosinophil count)?

Management of Eosinopenia (0.5 x10E3/uL)

An eosinophil count of 0.5 x10E3/uL is within normal range and does not require specific intervention unless associated with clinical symptoms or underlying conditions.

Understanding Eosinophil Counts

• Normal eosinophil count typically ranges from 0.0-0.5 x10E3/uL (or 0-500 cells/μL), making the value of 0.5 x10E3/uL at the upper limit of normal range 1
• Eosinopenia (abnormally low eosinophil count) is typically defined as <0.04 x10E3/uL (<40 cells/μL) 2
• The provided value of 0.5 x10E3/uL does not constitute eosinopenia and is considered normal 1

Clinical Significance of Eosinopenia

• True eosinopenia (<40 cells/μL) can be associated with:
  • Increased mortality risk in critically ill patients 2
  • Poorer outcomes in acute myocardial infarction 3
  • Potential marker for COVID-19 and other acute infections 4
  • Stress response with elevated cortisol levels 1
  • Medication effects, particularly corticosteroids 1

When to Consider Further Evaluation

• If the patient develops true eosinopenia (<40 cells/μL) in subsequent testing, consider:

  • Evaluating for underlying infections or inflammatory conditions 1
  • Medication review for agents that may suppress eosinophil counts 1
  • Assessment for stress response or adrenal dysfunction 1

• For patients with gastrointestinal symptoms and abnormal eosinophil counts:

  • Consider endoscopy with multiple biopsies to evaluate for eosinophilic esophagitis, which requires ≥15 eosinophils per high-power field on esophageal biopsy for diagnosis 5
  • Note that some patients with <15 eosinophils/HPF may still have eosinophilic esophagitis-like symptoms and benefit from treatment 6

Monitoring Recommendations

• For patients with borderline or low eosinophil counts without clear cause:

  • Monitor eosinophil counts with follow-up CBC in 4-6 weeks 1
  • If eosinophil count remains persistently low for more than 3 months without clear cause, consider referral to hematology 1

• For patients with travel history to endemic areas who develop eosinopenia:

  • Consider evaluation for parasitic infections, which can cause eosinophil abnormalities 1, 7
  • Note that some infections like strongyloidiasis typically cause eosinophilia but may present with eosinopenia during acute illness 7

Red Flags Requiring Urgent Attention

• Development of extreme eosinophilia during follow-up, which may indicate hypereosinophilic syndrome 1
• Persistent eosinopenia in critically ill patients, which has been associated with higher mortality 2