Understanding Absolute Neutrophil Count (ANC)
Neutrophils are a type of white blood cell (WBC) that play a critical role in fighting off bacterial infections. When a Complete Blood Count (CBC) with differential is ordered, it gives the percentage of neutrophils, but calculating the Absolute Neutrophil Count (ANC) is necessary to assess a patient's true risk of infection.
This is especially important in oncology, as chemotherapy often suppresses bone marrow function.
The ANC Formula
To find the ANC, you must combine the mature neutrophils (Polys/Segs) and the immature neutrophils (Bands), then multiply that percentage by the total WBC count.
Note: WBC counts are typically reported in thousands per microliter (K/µL). For example, a WBC of 4.5 K/µL is equal to 4,500 cells/µL. The ANC is typically expressed in standard cells/µL (or cells/mm³).
Neutropenia Severity Levels
Neutropenia is the medical term for an abnormally low level of neutrophils. The severity of neutropenia dictates the risk of opportunistic infections:
- Normal: 1,500 to 8,000 cells/µL. Normal risk of infection.
- Mild Neutropenia: 1,000 to 1,499 cells/µL. Minimal risk of infection.
- Moderate Neutropenia: 500 to 999 cells/µL. Moderate risk of infection.
- Severe Neutropenia: Below 500 cells/µL. High risk of severe, life-threatening infection. Often requires reverse isolation and prophylactic antibiotics.