Absolute neutrophil count

Absolute neutrophil count (ANC) is a measure of the number of neutrophil granulocytes^[1] (also known as polymorphonuclear cells, PMN's, polys, granulocytes, segmented neutrophils or segs) present in the blood. Neutrophils are a type of white blood cell that fights against infection.

The ANC is almost always part of a larger blood panel called the complete blood count. The ANC is calculated from measurements of the total number of white blood cells (WBC), usually based on the combined percentage of mature neutrophils (sometimes called "segs," or segmented cells) and bands, which are immature neutrophils.

Clinical significance

The reference range for ANC in adults varies by study, but 1500 to 8000 cells per microliter is typical. An ANC less than 500 cells/µL is defined as neutropenia and significantly increases risk of infection. Neutropenia is the condition of a low ANC, and the most common condition where an ANC would be measured is in the setting of chemotherapy for cancer.

Neutrophilia indicates an elevated count. While many clinicians refer to the presence of neutrophilia as a "left shift," this is imprecise, as a left shift indicates the presence of immature neutrophil forms, but neutrophilia refers to the entire mass of neutrophils, both mature and immature. Neutrophilia can be indicative of:

• Premature release of myeloid cells from the bone marrow.
• A leukemoid reaction.

Calculation

ANC = ${(\%neutrophils+\%bands)\times (WBC) \over (100)}$

or

ANC = (Absolute-Polys + Absolute-Bands)

In the above, we assume that the WBC is given in cells/µL (or thousand cells/mL, i.e. K/mL) such as 8,800 cells/µL or 8,800 K/mL; if the WBC were given in K/µL (instead of cells/µL or K/mL), such as 8.8 K/µL, you would first convert to cells/µL by multiplying the WBC by 1000.

The unit of ANC is cells per microliter of blood (abbreviated cells/µL; a microliter is equal to one cubic millimeter because 1,000,000 cubic millimeters are equal to one liter).

Ranges

NCI Risk Category	ANC
0	Within normal limits
1	≥1500 - <8.27
2	≥1000 - <1500/mm³
3	≥500 - <1000/mm³
4	< 500/mm³

Source: NCI CTC Toxicity scale Version 4.0

Related tests

In some cases, a ratio is reported in addition to the sum. This is known as the "I/T ratio".^[2][3]

References

1. Al-Gwaiz LA, Babay HH (2007). "The diagnostic value of absolute neutrophil count, band count and morphologic changes of neutrophils in predicting bacterial infections". Med Princ Pract. 16 (5): 344–7. doi:10.1159/000104806. PMID 17709921.
2. Walliullah SM, Islam MN, Siddika M, Hossain MA, Chowdhury AK (January 2009). "Role of Micro-ESR and I/T Ratio in the Early Diagnosis of Neonatal Sepsis". Mymensingh Med J. 18 (1): 56–61. PMID 19182751.
3. Russell GA, Smyth A, Cooke RW (July 1992). "Receiver operating characteristic curves for comparison of serial neutrophil band forms and C reactive protein in neonates at risk of infection". Arch. Dis. Child. 67 (7 Spec No): 808–12. doi:10.1136/adc.67.7_Spec_No.808. PMC 1590438. PMID 1519980.