How to Calculate Absolute Neutrophil Count (ANC)
Calculation Formula
The Absolute Neutrophil Count (ANC) is calculated by multiplying the total white blood cell (WBC) count by the percentage of neutrophils (segmented neutrophils plus bands). 1
The formula is:
- ANC = WBC count × (% segmented neutrophils + % bands) ÷ 100
For example, if a patient has:
- WBC count = 6,000 cells/mm³
- Segmented neutrophils = 50%
- Bands = 5%
- ANC = 6,000 × (50 + 5) ÷ 100 = 3,300 cells/mm³
Clinical Classification Based on ANC Values
Once calculated, the ANC is used to classify neutropenia severity 1:
- Normal ANC: >1,500 cells/mm³ (or >1.5 × 10⁹/L) 2
- Mild neutropenia: 1,000-1,500 cells/mm³ (or 1.0-1.5 × 10⁹/L) 1
- Moderate neutropenia: 500-1,000 cells/mm³ (or 0.5-1.0 × 10⁹/L) 1
- Severe neutropenia: <500 cells/mm³ (or <0.5 × 10⁹/L) 2, 1
Important Clinical Thresholds
Febrile neutropenia is defined as ANC <500 cells/mm³ (or <0.5 × 10⁹/L) with fever >38.5°C for >1 hour, which constitutes a medical emergency 2, 1.
Critical decision points for chemotherapy and monitoring 2:
- ANC ≥1,500 cells/mm³: Generally safe to proceed with chemotherapy 2
- ANC 1,000-1,500 cells/mm³: Hold chemotherapy until recovery, then resume at reduced dose 2
- ANC <1,000 cells/mm³: Hold chemotherapy and consider growth factor support 2
Automated vs Manual Counting
Automated hematology analyzers provide accurate and precise ANC measurements, even at very low levels (>0.1 × 10⁹/L), with acceptable correlation to manual counts (R² = 0.99). 3, 4 The automated method is preferred in clinical practice because it shortens turnaround time and maintains accuracy, though manual differential counts may be needed for verification in borderline cases 4.