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ANC Calculator — Absolute Neutrophil Count

Table of contents

What are neutrophils?What is neutropenia? — signs and symptomsWhat are the causes of neutropenia?What is the absolute neutrophil count?ANC formulaHow to calculate ANC? – interpreting the resultHow to treat neutropenia?Neutropenia complicationsANC as a biomarker

The ANC calculator (absolute neutrophil count calculator) is a tool that enables you to estimate the total count of neutrophils in the blood, which is helpful in the assessment of the risk connected with infectious diseases. An example of this is sepsis in patients undergoing chemotherapy. It allows for a quick diagnosis of neutropenia – a condition where the number of neutrophils in blood is substantially lowered.

In this article, we will describe what neutrophils are and what happens when their concentration in the blood significantly drops — neutropenia. Wondering what may cause this? We have also answered this question and explained how neutropenia is treated!

The indicator in evaluating neutropenia is absolute neutrophil count (ANC). In this article, you will learn more about ANC and how to interpret its result. You will also find out what the ANC formula is.

We try our best to make our Omni Calculators as precise and reliable as possible. However, this tool can never replace a professional doctor's assessment. If any health condition bothers you, consult a physician.

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What are neutrophils?

Neutrophils are the most numerous subpopulations of granulocytes and white blood cells. They are produced from the stem cells in bone marrow together with other granulocytes such as eosinophils, basophils, and agranulocytes — lymphocytes and monocytes. Every human produces approximately 1011 neutrophils daily [sic!], which live only for a few days.

Some of the neutrophils leaving bone marrow are so-called band neutrophils or band cells. These are cells that, although still immature, are just one step away from becoming fully matured segmented neutrophils. An increased level of band neutrophils, so-called bandemia or left shift, is the marker of increased production of white blood cells and the release of more white blood cells from bone marrow to the bloodstream. This reaction happens most often due to infection or inflammation of another kind.

Neutrophils are an essential part of the immune system, specifically the innate immune system. Their primary task is to participate in phagocytosis. They are recruited to the injury site within minutes following the beginning of the acute inflammatory process resulting, e.g., from the bacterial infection. Neutrophils then migrate from blood vessels to the interstitial tissue, where they phagocyte (kill and eat) bacteria. Together with bacteria, neutrophils are the main component of pus.

What is neutropenia? — signs and symptoms

Neutropenia is defined as a low neutrophil count. The generally accepted reference range for neutrophils is 1500 to 8000 cells per microliter (µl) of blood. However, most healthy people have more than 2000 neutrophils per microliter of blood. The lower the neutrophils, the more severe the neutropenia, the more probable complications, and the more dangerous they can be.

Three major mechanisms are involved in the development of neutropenia:

  1. Reduced production or ineffective granulopoiesis (production of granulocytes which takes place in bone marrow);
  2. Increased destruction or utilization of neutrophils; and
  3. A shift from the circulating (blood vessels) to the marginal pool (e.g., spleen in hypersplenism).

When may you suspect neutropenia?

The most important sign is vulnerability to infections, especially severe or recurrent bacterial infections of the skin, perirectal area, or mouth. Also, recurrent pneumonia is typical in patients with neutropenia. People with low absolute neutrophils often suffer from ulcers, abscesses, swollen gums, and mouth sores. They are also very often present with feverishness or low-grade fever, but also hypothermia is relatively common for these people.

Keep on reading to learn more about cancer-induced neutropenia and other causes of neutropenia.

What are the causes of neutropenia?

Yemenite Jews and other populations, including Ethiopian Jews and Bedouins, naturally have low neutrophil counts. This condition is called benign ethnic neutropenia because it is not associated with an increased risk of infection. Elsewhere neutropenia can be a hereditary disease (so-called severe congenital neutropenia), or it may develop as a symptom of a disease or a side effect of a treatment.

Diseases that may cause neutropenia include:

  • Infectious diseases, especially viral infections (HIV, Epstein-Barr Virus, Cytomegalovirus) and tuberculosis, malaria, and dengue fever;

  • Vitamin deficiency (especially vitamin B12 or folic acid);

  • Hematologic conditions (leukemias, aplastic anemia, myelodysplastic syndrome, myelofibrosis);

  • Congenital disorders and syndromes (severe congenital neutropenia, Kostman syndrome, Fanconi anemia, Diamond–Blackfan anemia);

  • Autoimmune diseases (rheumatoid arthritis – Felty's syndrome, systemic lupus erythematosus, autoimmune neutropenia, Crohn's disease); and

  • Hypersplenism (increased destruction of blood cells by the spleen because of its hyperfunction).

Absolute neutrophils may also be lowered as a result of treatment due to other conditions. These treatment methods and drugs include:

  • Cancer chemotherapy;

  • Radiation therapy;

  • Antibiotics, e.g., trimethoprim/sulfamethoxazole;

  • Anticonvulsants, e.g., valproate;

  • Antipsychotic, e.g., clozapine;

  • Antithyroid, e.g., propylthiouracil; and

  • Post-vaccination neutropenia.

Regardless of the primary reason, you should never forget that neutropenia can be life-threatening due to its complications and if you show symptoms of it, you should consult your doctor!

What is the absolute neutrophil count?

Absolute neutrophil count calculates total number of neutrophils, both mature and immature, in one microliter of blood. Measurement of ANC is vital in many clinical situations.

First of all, it is mandatory when diagnosing and classifying neutropenia. You cannot diagnose neutropenia without counting ANC! ANC is also a measure of the risk of infection, including severe and life-threatening infections like sepsis.

Additionally, the diagnosis of neutropenia imposes an obligation on the doctor to actively seek possible severe complications and try to prevent and treat them. Moreover, patients with such conditions should not receive certain drugs, so the administration of these will cease. That is why using the ANC formula and calculating absolute neutrophils is crucial.

ANC formula

The only data necessary to calculate a patient's ANC is the results of blood tests (routine and differential). You will need the following numbers:

  • The total number of white blood cells (WBC), measured in cells/μL;
  • Percentage of mature neutrophils (called segs or segmented cells);
  • Percentage of immature neutrophils (called bands).

Simply input all of these numbers into the ANC formula to calculate the absolute neutrophil count.

ANC = WBC × (segs[%] + bands[%]) / 100

The result, ANC, will also be measured in cells/μL.

Check out our other calculators that rely on the complete blood count (CBC) results: Absolute Reticulocyte Count calculator and Corrected Reticulocyte Count calculator!

How to calculate ANC? – interpreting the result

  1. Do a complete blood count (CBC). Remember that the results should be as recent as possible.

  2. Note down the number of white blood cells (WBC) per microliter. Let's assume it is equal to 6000 cells/μL.

  3. Write down the percentage of mature (segs) and immature (bands) neutrophils in your blood sample. Let's assume the percentage is equal to 30% for segs and 3% for bands.

  4. Insert all of the numbers into the ANC formula:

    ANC = WBC × (segs[%] + bands[%]) / 100

    ANC = 6000 × (30 + 3) / 100

    ANC = 6000 × 0.33

    ANC = 1980 cells/μL

  5. Compare the results against the following five interpretation rules.

The ANC results are divided into the following risk categories:

  • Category 0: ANC higher than 2000 cells/μL — Reference range: in typical adults, ANC ranges from 2000 to 8000 cells/μL.

  • Category 1: ANC between 1500 and 2000 cells/μL.

  • Category 2: ANC between 1000 and 1500 cells/μL — Mild neutropenia condition.

  • Category 3: ANC between 500 and 1000 cells/μL — Moderate neutropenia.

  • Category 4: ANC below 500 cells/μL — Severe neutropenia condition.

You should never forget that the value of ANC changes dynamically and reflects the patient's response to chemotherapy treatment or marrow transfer. It is often measured daily to assess whether the patient should receive additional antibiotics or bacteria cultures.

How to treat neutropenia?

How you manage neutropenia depends on its severity as well as the primary cause. Treatment is usually mandatory in the case of severe neutropenia. The treatment of choice in drug-induced neutropenia is discontinuation of the administration of the drug or, in cases of chemotherapy-induced neutropenia, lowering the dose of the drug.

In other cases, a treatment called granulocyte colony-stimulating factor (G-CSF) is used. This agent stimulates the production of every kind of white blood cell, including neutrophils, in bone marrow. This method treats many different types of neutropenia, including neutropenia induced by chemotherapy and radiation therapy. In some cases of severe bone marrow aplasia-induced neutropenia, stem cell transplantation is required.

Equally important as the usage of drugs are specific measures aimed at preventing infections. These include:

  • Hygiene;
  • Good dental care;
  • Avoiding contact with sick people;
  • Avoiding animal waste and not changing babies' diapers; and
  • Avoiding undercooked meat, raw fruits, and vegetables.

You should always remember that the primary objective in managing patients with neutropenia should be to prevent possibly life-threatening complications.

Neutropenia complications

Neutropenia can cause many types of infection, including severe central nervous system infections, sepsis, and recurrent skin infections. 70% of untreated patients with severe neutropenia die within the first 24-hours! This outcome is mainly caused by the two most important neutropenic complications: febrile neutropenia and neutropenic enterocolitis:

Febrile neutropenia

Severe neutropenia accompanied by a rapid onset fever is a medical emergency requiring immediate attention and treatment. Febrile neutropenia is generally defined as a rise in axillary temperature above 38.5 °C for more than one hour while having an absolute neutrophil count of fewer than 500 cells/μL.

Other definitions are also used, like having an axillary temperature exceeding 38 °C during one to four hours with severe neutropenia. Every second patient with such a condition already has an infection, and 40% of them have detectable bacteremia (presence of bacteria in the blood), which may lead to the development of neutropenic sepsis.

It is one of the most common life-threatening oncological emergencies, as it usually appears during chemotherapy.

In the early 1980s, it was recognized that, among other treatments, the early administration of broad-spectrum antibiotics would significantly reduce the mortality rate of patients with neutropenic fever. Nowadays, antifungal agents are often added to the treatment of febrile neutropenia. Administration of these drugs is usually discontinued when ANC > 500 cells/μL and fever abates.

Neutropenic enterocolitis / typhlitis

Neutropenic enterocolitis (also called typhlitis or caecitis) is an inflammation of the cecum (a part of the large intestine) associated with infection in a patient with low absolute neutrophils. Typhlitis should be suspected in a patient with neutropenia who reports diarrhea, bloating, abdominal tenderness, nausea, or vomiting. It is usually diagnosed with computed tomography. The treatment is based on antibacterial treatment and surgical treatment in cases of intestinal perforation.

ANC as a biomarker

Recently, many articles published in medical journals have reported results suggesting that ANC may be an independent prognostic factor for the success or failure of the therapy of different diseases. It has been proved, for example, in patients with:

  • Colorectal cancer;
  • Cervical cancer;
  • Acute lymphoblastic leukemia;
  • After liver transplantation; and
  • Newborns with sepsis.
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