Neutrophils (granulocytes) are the body’s main defense against bacterial infections and fungal infections. When neutropenia is present, the inflammatory response to such infections is ineffective.

Normal lower limit of the neutrophil count ranges from 1200-1500/μL. Neutrophil counts are not as stable as other cell counts and may vary considerably over short periods, depending on many factors such as activity status, anxiety, infections, and drugs. Thus, several measurements may be needed when determining the severity of neutropenia.