Absolute Neutrophil Count (ANC) Calculator

Variables and formula

Absolute neutrophil count is used in the assessment of neutropenic fever patients (for risk stratification), before antibiotic therapy is started.

The variables required by the calculator can be found in the results of a complete blood count:

■ Neutrophils in percentage;

■ Bands in percentage;

■ White blood cells in cells/µ.

The ANC formula used is:

Absolute neutrophil count = White blood cells count in 1000s x (% PMNs + % Bands) x 10

The tool displays the neutrophils per cubic millimeter but also the interpretation of the value, which is the neutropenia status.

ANC interpretation

The Absolute neutrophil count consists of both the segmented, mature and the bands, almost mature neutrophils.

This measure can be determined daily, during hospital admission, to check the immunocompromised patient’s status, the bone marrow’s response after chemotherapy or the response to antibiotic if the patient suffers from neutropenic fever.

Any value below 1500 cells/mm³ is considered to be neutropenia and there are three different degrees of severity:

■ Mild neutropenia: 1000-1500 cells/mm³

■ Moderate neutropenia: 500-999 cells/mm³

■ Severe neutropenia: <500 cells/mm³

ANC values can also be associated with the National Cancer Institute risk categories, as described in the table below:

About the study

The formula originated in 2007, after a study by Al-Gwaiz and Babay on 105 patients with bacteremia. Absolute neutrophil and neutrophil band count were performed and the neutrophils were evaluated for three types of morphologic changes:

■ Toxic granulation;

■ Vacuolation;

■ Dohle bodies.

The study found that ANC was more sensitive than neutrophil band count in predicting bacterial infections. The only limitation of ANC is in the assessment of infant and elderly patients.

Neutrophils guidelines

Neutrophils are one of the WBCs (alongside lymphocytes, monocytes, eosinophils and basophils) and are an important mediator of the immune response to bacteria and fungi.

PMNs (polymorphonuclear cells), as they are sometimes called, make up 60-70% of the circulating leukocytes and have a lifespan of about 5 days in circulation.

Their levels are commonly depressed during chemotherapy or radiation and require some time to readjust: the bone marrow needs time to produce, mature and release them in the blood stream.

Trauma and acute infections stimulate release of WBCs but the cells may not be entirely mature, thus are released as bands (the incompletely matured version).

Acute infections and trauma stimulate their release and elevate the overall WBC count but one of the common problems incurred in such situations is that the neutrophils released might not be completely matured and are released in the form of bands, the incompletely matured version.

ANC values reflect the immunological status and can predict subsequent neutropenic fever. These are carefully monitored during abx therapy and bone marrow suppression.

Original source

Al-Gwaiz LA, Babay HH. The diagnostic value of absolute neutrophil count, band count and morphologic changes of neutrophils in predicting bacterial infections. Med Princ Pract. 2007; 16(5):344-7.

Validation

Newman T et al. Interpreting Complete Blood Counts Soon After Birth in Newborns at Risk for Sepsis. Pediatrics. 2010; 126(5): 903–909.

Other references

1. Klastersky J, Paesmans M, Rubenstein EB, Boyer M, Elting L, Feld R, Gallagher J, Herrstedt J, Rapoport B, Rolston K, Talcott J. The Multinational Association for Supportive Care in Cancer risk index: A multinational scoring system for identifying low-risk febrile neutropenic cancer patients. J Clin Oncol. 2000; 18(16):3038-51.

2. Carmona-Bayonas A et al. Prediction of serious complications in patients with seemingly stable febrile neutropenia: validation of the Clinical Index of Stable Febrile Neutropenia in a prospective cohort of patients from the FINITE study. J Clin Oncol. 2015; 33(5):465-71.