The absolute neutrophil count (ANC) is the total number of neutrophils in the white blood cell (WBC) count. It’s typically part of the complete blood count (CBC) with differential. While some labs calculate the ANC for us, it’s important to know just what is involved in the calculation as this number is often used to assess infection risk and guide cancer treatment.

Remember that neutrophils are the most common type of WBC and they lead the immune response. A decrease in the number of neutrophils typically means a patient is at increased risk of infection.

You can calculate the ANC by multiplying the total number of WBCs by the percentage of neutrophils and dividing by 100 (Coates, 2023). Sometimes, you may see the percent of neutrophils referred to as polymorphonuclear (PMN) cells and you may have young neutrophils (also called bands) on your laboratory report. In this case, add the percent of neutrophils (PMNs) and percent of bands (and divide by 100) before multiplying by the WBC.
 

Let’s try an example.

If the WBC count is 6.3 thousand/uL, and neutrophils are 56.1% and bands are 3%, what is the ANC?
ANC = WBC (cells/uL) x [percent (PMNs + bands) ÷ 100]
ANC = 6,300 cells/uL x [(56.1%+3%) ÷ 100]
ANC = 6,300 cells/uL x (59.1% ÷ 100)
ANC = 6,300 cells/uL x 0.591
ANC = 3,720 cells/uL

So, what does this mean?

As we mentioned, the ANC is an indicator of infection risk. Neutropenia (decreased neutrophils) is usually defined as an ANC less than 1,500 cells/uL in an adult and can be categorized as mild, moderate, or severe.
 

Categorizing Neutropenia (Berlinger, 2022)
Category	ANC
Mild	1,000 to less than 1,500 cells/uL
Moderate	500 to less than 1,000 cells/uL
Severe	Less than 500 cells/uL

Example #2

JD is a 42-year-old who presents with progressive fatigue. Physical examination is notable for splenomegaly and lymphadenopathy. Results from his CBC with differential are:

White Blood Cells           1.2 THO/uL       
Hemoglobin                    10.7 g/dL           
Hematocrit                      31 %     
Platelets                          262 THO/uL      
% Neutrophils                 70.1 % 
% Lymphocytes              30.8 % 
% Monocytes                  9.5 %    
% Eosinophils                 2.4 %    
% Basophils                    1.2 %    
% Bands                          3%  

Based on these results, let’s calculate JD’s ANC.

ANC = WBC (cells/uL) x [percent (PMNs + bands) ÷ 100]
ANC = 1,200 cells/uL x [(70.1%+3%) ÷ 100]
ANC = 1,200 cells/uL x (73.1% ÷ 100)
ANC = 1,200 cells/uL x 0.731
ANC = 877.2 cells/uL
 
JD has moderate neutropenia and will need further evaluation to uncover the cause.

Neutropenia may be discovered while evaluating other signs and symptoms, as in the case of JD, or as an incidental finding on a routine CBC. In either circumstance, further evaluation to determine any underlying pathology and potential medical emergencies is necessary. It’s also important to be aware that most patients on chemotherapy will experience a nadir, or lowest value, in ANC five to ten days after completion of a chemotherapy session.

References:

Berliner, N. (2022, June 3). Approach to the adult with unexplained neutropenia. UpToDate. https://www.uptodate.com/contents/approach-to-the-adult-with-unexplained-neutropenia

Coates, T.D. (2023, August 11). Laboratory evaluation of neutrophil disorders. UpToDate. https://www.uptodate.com/contents/laboratory-evaluation-of-neutrophil-disorders

 

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