Unit Converter
Neutrophils (Absolute Neutrophil Count)
Synonyms
- Absolute neutrophil count
- ANC
- Neutrophils (Abs)
- Neutrophil number
- Polymorphonuclear cells (PMNs)
- Granulocytes (neutrophils)
Units of Measurement
All these units represent the same absolute count:
- 10⁹/L
- G/L
- Gpt/L
- cells/L
- 10³/µL
- 1000/µL
- 10³/mm³
- 1000/mm³
- K/µL
- K/mm³
- cells/µL
- cells/mm³
Universal Conversion
1 ×10⁹/L=1000 cells/µL=1 K/µL1\ \text{×10⁹/L} = 1000\ \text{cells/µL} = 1\ \text{K/µL}1 ×10⁹/L=1000 cells/µL=1 K/µL
Examples:
- 3.0 ×10⁹/L = 3000 cells/µL = 3.0 K/µL
- 0.5 ×10⁹/L = 500 cells/µL = neutropenia
Description
Neutrophils are the most abundant type of white blood cell (40–70%).
They are the primary responders against:
- Bacterial infections
- Fungal infections
- Acute inflammation
ANC equals:
\text{ANC} = \text{WBC} \times (\text{% Neutrophils + % Bands})
The absolute neutrophil count is the single most important marker of innate immune function.
Physiological Role
1. First-line defense
Rapid response to bacterial invasion.
2. Phagocytosis
Engulf pathogens & debris.
3. Release of enzymes and reactive oxygen species
Kills microbes effectively.
4. NETosis
Neutrophil extracellular traps capture microbes.
5. Inflammation
Central to acute inflammatory response.
Clinical Significance
HIGH Neutrophils (Neutrophilia)
(ANC > 7.5 ×10⁹/L in adults)
Causes
1. Infections (most common)
- Bacterial
- Fungal
- Acute viral (early phase)
- Sepsis
2. Inflammatory States
- Rheumatoid arthritis
- Vasculitis
- IBD
- Trauma
3. Stress Reactions
- Surgery
- Burns
- Seizures
- MI
- Intense exercise
4. Smoking
5. Medication-induced
- Steroids
- Lithium
- G-CSF
6. Hematologic Diseases
- Myeloproliferative neoplasms (CML, PV)
- Leukemoid reaction (>50,000/µL)
LOW Neutrophils (Neutropenia)
A major clinical concern due to infection risk.
Severity Classification
- Mild: 1.0–1.5 ×10⁹/L
- Moderate: 0.5–1.0 ×10⁹/L
- Severe: <0.5 ×10⁹/L
- Agranulocytosis: <0.2 ×10⁹/L
Causes
1. Viral Infections
Most common cause of mild neutropenia.
2. Drug-induced
- Chemotherapy
- Anti-thyroid drugs
- Clozapine
- Sulfonamides
- Anti-epileptics
3. Bone Marrow Disorders
- Aplastic anemia
- Myelodysplastic syndromes
- Leukemia
- Marrow infiltration (cancer)
4. Autoimmune Neutropenia
- SLE
- RA (Felty’s syndrome)
5. Nutritional Deficiency
- B12 deficiency
- Folate deficiency
- Copper deficiency
6. Congenital Neutropenia
- Kostmann syndrome
- Cyclic neutropenia
7. Hypersplenism
Clinical Risk
- ANC < 0.5 ×10⁹/L → high risk of life-threatening infection
- ANC < 0.2 ×10⁹/L → medical emergency
Reference Intervals
Adults
- 2.0 – 7.5 ×10⁹/L
(= 2000–7500 cells/µL)
Children
Higher in early childhood:
| Age | Normal ANC |
| Newborn | 6.0 – 26.0 ×10⁹/L |
| 1–6 years | 1.5 – 8.5 ×10⁹/L |
| >6 years | 1.5 – 7.5 ×10⁹/L |
Diagnostic Uses
1. Infection Evaluation
Neutrophils rise in bacterial and fungal infections.
2. Sepsis Risk Assessment
Extremely low ANC → high mortality.
3. Chemotherapy Monitoring
ANC guides:
- Treatment cycles
- Need for G-CSF
- Infection prophylaxis
4. Autoimmune & Hematologic Disease Assessment
Neutropenia suggests marrow failure or autoimmune destruction.
5. Emergency Medicine
High ANC indicates acute stress or severe infection.
Analytical Notes
- Automated CBC analyzers calculate ANC from WBC × differential %
- Manual smear needed when WBC morphology suspicious
- Steroid therapy can mask infections by increasing ANC
- Bands (immature neutrophils) included in ANC (“left shift”)
Clinical Pearls
- Left shift (↑ bands) + neutrophilia = strong bacterial infection clue.
- ANC < 500/µL = neutropenic sepsis risk → requires urgent antibiotics.
- Viral infections frequently cause mild transient neutropenia.
- ANC is more clinically important than the neutrophil percentage.
- Smoking causes mild chronic neutrophilia.
Interesting Fact
Neutrophils live for only 6–10 hours in circulation but are produced in enormous numbers - over 100 billion per day — showcasing their central role in immune defense.
References
- Tietz Clinical Chemistry & Molecular Diagnostics, 8th Edition - Hematology
- WHO Hematologic Reference Standards
- Mayo Clinic Laboratories - ANC
- ARUP Consult - WBC Differential Interpretation
- IDSA Guidelines - Neutropenia & Infection Risk
- MedlinePlus / NIH - Neutrophil Count