Normal Absolute Neutrophil Count
A normal absolute neutrophil count (ANC) is above 1,500 cells per microliter (1.5 × 10⁹/L), which indicates adequate protection against infections. 1
Understanding ANC Values
The ANC threshold of 1,500 cells/µL serves as the critical dividing line between normal and neutropenic states across multiple guideline sources. 1, 2, 3
Key reference ranges:
- Normal ANC: >1,500 cells/µL - This represents adequate neutrophil levels for infection defense 1
- Subnormal range: 1,500-1,800 cells/µL - Technically below the upper normal limit but not classified as neutropenia 4
- Mild neutropenia: 1,000-1,500 cells/µL - Slightly increased infection risk 1, 5
- Moderate neutropenia: 500-1,000 cells/µL - Moderate infection risk 5, 6
- Severe neutropenia: <500 cells/µL - High risk of serious infections 1, 5
- Profound neutropenia: <100 cells/µL - Very high risk of life-threatening infections 1
Clinical Context for Monitoring
The baseline white blood cell count requirement of at least 3,500/mm³ is specifically mandated before initiating clozapine therapy, with ANC monitoring thresholds established for medication safety. 7
Clozapine-specific ANC thresholds require immediate action:
- Stop medication immediately if ANC drops below 1,000/mm³ and monitor daily for infection 7
- Stop medication if ANC drops to 1,000-1,500/mm³, resume only when ANC >1,500/mm³ with no infection signs 7
- Increase monitoring to biweekly if ANC is 1,500-3,000/mm³ until WBC exceeds 3,500/mm³ 7
Calculation Method
The ANC is calculated by multiplying the total white blood cell count by the percentage of neutrophils (segmented neutrophils plus bands). 1, 5 This calculation is derived from a standard complete blood count with differential.
Clinical Significance of Normal Values
Maintaining an ANC above 1,500 cells/µL ensures the body's first line of defense against bacterial and fungal infections remains intact. 1 When the ANC falls below this threshold, infection risk increases in a dose-dependent manner, with progressively lower counts conferring exponentially higher risks of serious complications. 4