What Are Neutrophils in a Blood Test?

Neutrophils are the most abundant white blood cell (40–60% of WBC). They are your immune system's first responders against bacterial infections.

Normal Range

• Absolute: 2,500–7,000/µL
• Percentage: 40–60%

High Neutrophils (Neutrophilia)

• Bacterial infection — most common cause
• Physical stress — exercise, surgery, trauma
• Inflammation
• Smoking
• Corticosteroids
• Myeloproliferative disorders

Low Neutrophils (Neutropenia)

• Chemotherapy — most common cause in cancer patients
• Viral infection
• Autoimmune disease
• Certain medications
• B12 or folate deficiency
• Severe malnutrition

Severity of Neutropenia

• Mild: 1,000–1,500/µL
• Moderate: 500–1,000/µL
• Severe: below 500/µL — high infection risk, febrile neutropenia is an emergency

Left Shift

• Increased immature neutrophils (bands) = active bacterial infection, bone marrow releasing stored cells