Upper Limit of Normal for Blood Eosinophils in Blood Count

Normal Range and Clinical Significance

• The upper limit of normal for blood eosinophils in a complete blood count is 0.45 × 10^9/L (450 cells/μL) 1
• Hypereosinophilia (HE) is formally defined as >1.5 × 10^9/L eosinophils in the blood on two examinations at least one month apart 2

Clinical Applications and Interpretation

• In eosinophilic esophagitis (EoE), peripheral eosinophilia occurs in 10-50% of adults and 20-100% of children, though usually only modestly elevated (2-fold) 3
• Blood eosinophil levels above 0.24 × 10^9/L (240 cells/μL) can predict high tissue eosinophilia with sensitivity 70.9% and specificity 78.4% 4

Clinical Relevance in Specific Conditions

• In returning travelers and migrants from tropical regions, eosinophilia (>0.45 × 10^9/L) is common (8-10%) and often associated with helminth infections 1
• In asthma, the upper limit of normal for sputum eosinophil differential count is 1.9%, which differs from blood eosinophil normal ranges 5