What Is an Absolute Neutrophil Count (ANC)?

An absolute neutrophil count (ANC) is a blood test that measures the amount of a specific white blood cell—called a neutrophil—in a sample of blood. The ANC is used to check for check signs of infection and inflammation as well as certain cancers like leukemia and lymphoma.

A high neutrophil count may indicate the presence of an infection or inflammatory disease, while a neutrophil count lower than 500 can place you at an increased risk of infection.

This article explains what an absolute neutrophil count test is, how the results are interpreted, and what it means if your ANC is high or low.

What Is an Absolute Neutrophil Count Test?

Your healthcare may order an ANC test as part of a battery of tests whenever there are symptoms of an infection or illness. The ANC is part of a common blood test called a complete blood count (CBC) that evaluates the composition, proportion, characteristics, types, and numbers of red blood cells, white blood cells, and platelets in a sample of blood.

White blood cells (WBCs) are an important part of your immune system and will increase whenever there is a disease or infection. Neutrophils, produced by your bone marrow, are among the "first responders" to any disease or infection.

Neutrophils make up roughly 50% of your total WBCs. Rather than isolating and counting each neutrophil individually, the ANC is calculated simply by multiplying your total WBCs by 50%.

Therefore, if your total WBCs count is 8,000, your ANC is 4,000 (8,000 x 50%). These numbers are reported as cells per microliter of blood (cells/mcL).

This number is then compared against a reference range of values. These are the low and high values between which a neutrophil count is considered normal. These values are derived from what is seen in specific populations of people.

Anything below or above the reference range of values is flagged in the lab report as a possible sign of a medical concern.

Interpreting ANC Results

The reference range of values for an ANC test can vary based on a person's age and other factors. With that said, most labs in the United States consider a normal ANC to be between 2,500 and 6,000 cells/mcL. Anything above or below this range of values is considered abnormal.

Abnormal ANC values are interpreted as follows:

• A low absolute neutrophil count is referred to as neutropenia. This occurs when the ANC is less than 2,500 cells/mcL. At levels below 1,000, you are at an increased risk of infection.
• A high absolute neutrophil count is called neutrophilia. This occurs when the ANC is over 6,00 cells/mCL. An ACN over 11,000 is a strong indication that your body is fighting a disease or infection.

In neither instance can an ANC test reveal what is causing the abnormal count. The test is simply the entry point from which a healthcare provider can expand the evaluation to narrow the possible causes.

For neutropenia, the healthcare provider will want to know why the bone marrow is unable to supply ample neutrophils to defend the body against disease or infection. For neutrophilia, the healthcare provider will want to know what is causing the bone marrow to produce excessive neutrophils.

Why Is My Absolute Neutrophil Count Low?

Neutropenia is mainly caused by the suppression of your bone marrow. There are diseases, infections, and medications that can cause this. Neutropenia can also occur with certain cancers and, on the flip side, as a side effect of cancer treatment.

Cancers associated with neutropenia include:

• Leukemia
• Myeloma
• Non-Hodgkin lymphoma (NHL)

Neutropenia is common with viral and bacterial infections such as:

• Chickenpox
• COVID-19
• Cytomegalovirus
• Epstein-Barr virus
• Hepatitis A virus
• Hepatitis B virus
• Hepatitis C virus
• HIV
• Lyme disease
• Measles
• Mumps
• Pertussis (whooping cough)
• Salmonella
  
• Sepsis
• Shingles
• Tuberculosis

There are certain diseases that affect the bone marrow directly, including:

• Aplastic anemia
• Chronic primary neutropenia
• Myelodysplastic syndrome
• Myelofibrosis

Certain medications and medical treatments can suppress the bone marrow, particularly when prescribed at high doses or use on an ongoing basis. These include:

• Antibiotics
• Anticonvulsants
• Antidepressants
  
• Antimalarial drugs
• Antipsychotics
• Antiviral drugs
• Cardiac arrhythmia drugs
• Chemotherapy
• Hyperthyroid drugs
  
• Nonsteroidal anti-inflammatory drugs (NSAIDs)
• Radiation therapy

If you have a low neutrophil count, the first course of treatment is to resolve the underlying cause. This may include stopping or adjusting medications that cause neutropenia.

There are also drugs like Neupogen (filgrastim) that stimulate white blood cell growth in people with cancer. Your healthcare provider might also order a transfusion of white blood cells.

What Does a High Absolute Neutrophil Count Mean?

Neutrophilia means that some sort of inflammatory process is going on in your body and your immune system has launched a defense by producing more neutrophils. Certain medications are also known to do this.

Infections associated with neutrophilia are typically caused by bacteria as well as certain viruses, fungi, and parasites. In some cases, an infection may cause a steep rise in neutrophils (neutrophilia) followed by a steep drop (neutropenia) as the immune battle wages on.

Some of the more common infections associated with neutrophilia are:

• Epstein-Barr virus
• Herpes simplex virus
• Leptospiral infections
• Pneumococcal infections
• Staphylococcal infection
• Varicella-zoster virus (associated with chickenpox and shingles)

Inflammatory disease or conditions associated with neutrophilia include:

• Ankylosing spondylitis
• Blood loss
• Chronic obstructive pulmonary disease (COPD)
• Crohn's disease
• Cushing syndrome
• Diabetic ketoacididois
• Eclampsia and pre-eclampsia
• Gout
• Heart attack
• Hypoxia (lack of oxygen)
• Kidney failure
• Lupus
• Psoriatic arthritis
• Rheumatoid arthritis
• Scleroderma
• Sickle cell disease
• Severe burns or skin trauma
• Smoking
• Ulcerative colitis

Medications known to cause neutrophilia include:

• Clozaril (clozapine)
• Corticosteroids (steroids)
• Epinephrine (adrenaline)
• Heparin
• Lithium
• Minocin (minocycline)
• Retin-A (tretinoin)
  

There are also certain specific blood cancers that can cause high neutrophil counts:

• Chronic myelocytic leukemia (CML)
• Hodgkin lymphoma (HL)
  
• Juvenile myelomonocytic leukemia (JML)

As with neutropenia, neutrophilia doesn't cause symptoms per se. Rather, the diseases or conditions that cause neutrophilia can manifest with symptoms.

Summary

Neutrophils are a type of white blood cell that help your body fight infection. An ANC test measures the number of neutrophils in your blood. In most healthy people, more than 50% of white blood cells are neutrophils.

Your neutrophils might be low or high for various reasons, including an infection, certain inflammatory diseases, leukemia, lymphoma, and certain medications.