 Informally, blood eosinophil levels are often regarded as mildly elevated at counts of 500–1,500/μL, moderately elevated between 1,500–5,000/μL, and severely elevated when greater than 5,000/μL.Elevations in blood eosinophil counts can be transient, sustained, recurrent, or cyclical.Eosinophil counts in human blood normally range between 100–500 per/μL.