Neutrophils
Neutrophils· also: Neutrophils, ANC, Polys, Segs
Clinical Overview
Neutrophils are the most abundant white blood cells and the primary responders to bacterial infections. They engulf and destroy bacteria through phagocytosis. The absolute neutrophil count (ANC) is the key measure of the body's ability to fight bacterial and fungal infections.
Why This Test Matters
The absolute neutrophil count (ANC) is the most clinically actionable WBC differential value. Severe neutropenia (ANC <500/µL) renders patients highly vulnerable to life-threatening bacterial and fungal infections. Neutrophilia points to active infection, inflammatory states, or myeloid malignancy. Immature neutrophils ("bands" or "left shift") in the blood indicate overwhelming infection or bone marrow stress.
Reference RangesWHO/IFCC standards
| Age Group | Reference Range | Unit | Notes |
|---|---|---|---|
| Adults (18–64) | 1.8 – 7.7 | ×10³/µL | Absolute Neutrophil Count (ANC) |
Also reported in: %.
Critical (Panic) Values
Critical Low: < 0.5 ×10³/µL. Values outside these limits require immediate clinical attention.
What Causes Abnormal Results?
High Neutrophils Causes
- Bacterial infection (most common)
- Physiological stress (surgery, trauma, myocardial infarction)
- Corticosteroid use
- Chronic myeloid leukemia (CML)
- Smoking
- Inflammatory bowel disease
- Obesity
Low Neutrophils Causes
- Chemotherapy or radiation therapy (most common cause of severe neutropenia)
- Viral infections (HIV, EBV, hepatitis)
- Autoimmune neutropenia
- Aplastic anemia
- Clozapine and other medications
- Severe sepsis (neutrophil consumption)
- Vitamin B12 or folate deficiency
- Ethnic neutropenia (benign, common in people of African ancestry)
Signs & Symptoms to Watch For
How to Prepare for This Test
No special preparation. Part of the CBC differential count.
Factors That Can Affect Results
- Time of day (slight circadian variation)
- Steroids (mobilize neutrophils from vessel walls, raising count)
- Ethnicity (people of African ancestry commonly have lower baseline neutrophil counts — benign ethnic neutropenia)
Related Topics
Frequently Asked Questions
What is a safe neutrophil count for starting chemotherapy?
Most oncology protocols require an ANC of at least 1,000–1,500/µL before starting a new cycle of chemotherapy. Below this threshold, the risk of febrile neutropenia — a potentially fatal infection complication — is too high. G-CSF (filgrastim) is used between cycles to speed neutrophil recovery.
What is febrile neutropenia?
Febrile neutropenia is defined as a fever (≥38.3°C or sustained 38°C) in a patient with an ANC below 500/µL. It is a medical emergency requiring broad-spectrum intravenous antibiotics within one hour of presentation, even before blood culture results are available.
What is ethnic neutropenia and is it harmful?
Ethnic neutropenia (also called benign ethnic neutropenia) is a normal variant in which people of African, Middle Eastern, or West Indian ancestry have a lower baseline neutrophil count (sometimes ANC 1,000–1,500/µL) without increased infection risk. It is caused by a variant in the DARC gene and is not a disease. Recognition is important to avoid unnecessary investigations or delay in chemotherapy.