How to Calculate the Absolute Neutrophil Count (ANC)
The ANC is calculated by multiplying the total white blood cell (WBC) count by the percentage of neutrophils (segmented neutrophils plus bands), as recommended by the American College of Physicians. 1
The Calculation Formula
ANC = WBC count × (% segmented neutrophils + % bands) ÷ 100
For example:
- If WBC = 5,000 cells/μL
- Segmented neutrophils = 50%
- Bands = 5%
- ANC = 5,000 × (50 + 5) ÷ 100 = 2,750 cells/μL or 2.75 × 10⁹/L 1
Key Components Required
You need two values from the complete blood count (CBC) with differential:
- Total WBC count (reported in cells/μL or × 10⁹/L) 1
- Percentage of neutrophils, which includes:
Automated vs. Manual Calculation
Automated hematology analyzers (such as Cell-Dyn 3500, Sysmex XE-2100, or Advia 2120i) provide accurate and precise ANC values even at very low levels (>0.1 × 10⁹/L), with excellent correlation to flow cytometric methods. 2
- Automated 5-part differential instruments show very good precision and accuracy for ANC determination, though a small systematic difference (approximately 10%) may exist between different instrument types 2
- Manual differential counts using 100-cell differentials correlate well with automated methods (R² = 0.99), though differences can range from -55% to +33% of the manual value 3
- For clinical decision-making regarding chemotherapy administration, automated ANC values are adequate and reduce turnaround time between specimen collection and result verification 3
Clinical Interpretation Thresholds
Once calculated, interpret the ANC using these classifications from the National Comprehensive Cancer Network:
- Normal: ANC ≥2.0 × 10⁹/L (2,000/μL) 1
- Mild neutropenia: ANC 1.0-1.5 × 10⁹/L 1, 4
- Moderate neutropenia: ANC 0.5-1.0 × 10⁹/L 1, 4
- Severe neutropenia: ANC <0.5 × 10⁹/L 1, 4
Common Pitfalls to Avoid
Do not interpret ANC in isolation—always consider the entire blood count picture including hemoglobin and platelet levels, as recommended by the National Comprehensive Cancer Network. 1
- Failing to add both segmented neutrophils AND bands when calculating the neutrophil percentage leads to underestimation of ANC 1
- Not distinguishing between disease-related and treatment-related causes of abnormal ANC 1
- Overlooking trends in serial ANC measurements rather than focusing on single isolated values 1
- For patients on myelosuppressive therapy, the National Comprehensive Cancer Network recommends monitoring CBC twice weekly to track ANC trends 5