Neutrophils are a type of white blood cell that help heals damaged tissues and resolves infections. Neutrophil levels can increase or decrease in response to infections, injuries, drug treatments, certain genetic conditions, and stress.

  • Neutrophils are the most common type of white blood cell in the body, which makes them a first line of defense to heal injuries and fight infections.
  • The amount of neutrophils in the blood typically increases if a person is sick or injured to help their body heal.
  • Neutrophil levels may decrease if a person has a long-term infection, cancer, an autoimmune condition, or is taking certain medications.

Neutrophils help prevent infections by blocking, disabling, digesting, or warding off invading particles and microorganisms. They’re constantly searching for signs of infection, and quickly respond to trap and kill pathogens.

They also communicate with other cells to help them repair damaged cells and mount an immune response. Neutrophils play an important role in regulating the immune system and inflammation in your body.

The body produces neutrophils in the bone marrow, and they account for 50–70% of all white blood cells in the bloodstream. A typical overall white blood cell level in the bloodstream for an adult is somewhere between 4,500–11,000 per millimeters cubed (mm3).

When there is an infection or another source of inflammation in the body, special chemicals alert mature neutrophils, which then leave the bone marrow and travel through the bloodstream to the site in need.

Band cells are an immature form of neutrophil produced when your body is fighting an infection or inflammation. An excess of band cells in the blood is called bandemia. When this occurs, it’s typically an indication that an infection or inflammation is present.

Unlike some other cells or blood components, neutrophils can travel through junctions in the cells that line blood vessel walls and enter into tissues directly.

In this article, we look at the reasons for high or low neutrophil levels, how doctors can test these levels, and what typical neutrophil levels are for different groups.

A note about sex and gender

Sex and gender exist on spectrums. This article will use the terms “male,” “female,” or both to refer to sex assigned at birth. Click here to learn more.

There are many reasons why a person may have higher or lower levels of neutrophils in their blood.

High levels

Having an abnormally high level of neutrophils in the blood is called neutrophilic leukocytosis, also known as neutrophilia.

Rises in neutrophil levels usually occur naturally due to infections or injuries. However, neutrophil blood levels may also increase in response to:

  • some medications, such as corticosteroids, beta-2-agonists, and epinephrine
  • some cancers
  • physical or emotional stress
  • surgery or accidents
  • smoking tobacco
  • pregnancy
  • having obesity
  • genetic conditions, such as Down syndrome
  • surgical removal of the spleen

Some inflammatory conditions can increase neutrophil levels, including rheumatoid arthritis, inflammatory bowel disease, hepatitis, and vasculitis.

Low levels

An abnormally low level of neutrophils in the blood is called neutropenia.

A drop in neutrophil blood levels typically occurs when the body uses immune cells faster than it produces them or the bone marrow is not producing them correctly.

An enlarged spleen may also cause a decrease in neutrophil levels. This is because the spleen traps and destroys neutrophils and other blood cells.

Some conditions and procedures that cause the body to use neutrophils too quickly include:

  • severe or chronic bacterial infections
  • allergic disorders
  • certain drug treatments
  • autoimmune disorders

Some specific conditions, procedures, and drugs that interfere with neutrophil production include:

  • cancer
  • viral infections, such as influenza
  • bacteria infections, such as tuberculosis
  • myelofibrosis, a disorder that involves bone marrow scarring
  • vitamin B12 deficiency
  • radiation therapy involving bone marrow
  • phenytoin and sulfa drugs
  • chemotherapy medications
  • toxins, such as benzenes and insecticides
  • aplastic anemia, which is when the bone marrow stops producing enough blood cells
  • severe congenital neutropenia, a group of disorders where neutrophils cannot mature
  • cyclic neutropenia, which causes cell levels to rise and fall
  • chronic benign neutropenia, which causes low cell levels for no apparent reason

Doctors can identify changes in neutrophil levels using a blood test called a complete blood count (CBC) with differential, which identifies specific groups of white blood cells.

A doctor may order a CBC test when someone is experiencing a range of symptoms related to infection, chronic illness, or injuries, such as fever, pain, and exhaustion. A nurse or technician will draw a small amount of blood from the arm and send it away for evaluation.

If the initial test shows a higher or lower number of white blood cells than expected, the doctor will likely repeat the test to confirm the results. If the initial results are confirmed, a doctor will perform a physical exam, ask questions about the person’s lifestyle, and review their medical history.

If there is no apparent reason for changes in white blood cell levels, the doctor will order more specific tests.

These can include:

  • CT scans
  • blood cultures
  • urine sample analysis
  • a chest X-ray

After a blood test, experts will examine the sample to see if there are any specific white blood cells, such as immature neutrophils called myeloblasts. During an infection or chronic illness, these cells emerge from the bone marrow and mature in the blood instead of the bone marrow.

If myeloblasts or other white blood cells appear in significant levels in the blood, the doctor will request a bone marrow sample.

Bone marrow collection involves inserting a long needle into part of the pelvis near the back of your hip. The procedure can be painful, and a doctor will typically take the sample in a hospital setting using at least a local anesthetic.

Changes in neutrophil levels are often a sign of more significant changes in white blood cell levels.

The amount and proportion of white blood cells in the bloodstream change over time with age and other events, such as pregnancy. While everyone’s typical range is slightly different, some commonly used ranges include:

Newborn13,000–38,000 per mm3
Infant 2 weeks of age5,000–20,000 per mm3
Adult4,500–11,000 per mm3
Pregnant female (third trimester)5,800–13,200 per mm3

In adults who are not pregnant, a white blood cell blood count over 11,000 per mm3 is considered high. Neutrophilic leukocytosis occurs when a person has over 7,000 per mm3 mature neutrophils in their bloodstream.

The lower blood level limit for neutrophils in human blood is 1,500 per mm3. When a person’s levels of neutrophils are low, it is known as neutropenia. The lower the level of neutrophils circulating in the blood, the more severe neutropenia. Neutropenia levels are:

Mild neutropenia1,000–1,500 per mm3
Moderate neutropenia500–999 per mm3
Severe neutropeniabelow 499 per mm3

Minor changes in neutrophil or white blood cell levels are typically nothing to worry about as long as they are temporary. A raised white blood cell count often means the body is responding to infection, injury, or stress.

Some people have naturally lower levels of white blood cells and neutrophils than other people. This can be due to a range of factors, including congenital conditions.

If neutrophil or white blood cell levels are significantly altered for no apparent reason or remain raised or lowered, a doctor will order tests to determine the cause.

Severely high or low levels of white blood cells often require emergency care and monitoring. People with severe neutropenia will have inadequate defense against infection.

People with severe neutrophilia typically have a life threatening infection or other inflammatory illness that requires treatment, such as cancer.

The best way to correct abnormal neutrophil levels is to address and treat the underlying cause.

How to lower neutrophil levels

Neutrophilia typically occurs when the body is fighting infection or inflammation from an illness or injury. Lowering your neutrophil levels involves treating the underlying cause of neutrophilia.

Treatment to lower your neutrophil levels will depend on the cause of neutrophilia and may include the use of:

  • antibiotic therapy
  • anti-inflammatory therapy
  • hydration therapy (IV)
  • chemotherapy

People with altered neutrophil levels caused by medications or procedures may need to stop or adjust treatments.

How to raise neutrophil levels

Raising your neutrophil levels involves treating the underlying cause of neutropenia.

If you have chronic conditions that disrupt your neutrophil production, you may need to take drugs that allow the body to increase neutrophil production, such as:

  • colony-stimulating factors
  • corticosteroids
  • bone marrow or stem cell transplantation
  • antibiotics to help prevent infection

People with severely low levels of neutrophils often require monitoring, antibiotic therapy, and hospitalization to reduce the risk of severe infection.

Neutropenia can sometimes be caused by a deficiency of vitamin B12, also known as cobalamin, and vitamin B9, known as folate.

Eating foods rich in vitamins B9 or B12 or taking these as supplements may help improve low neutrophil blood levels.

Examples of foods rich in vitamin B12 include:

  • eggs
  • milk and other dairy products
  • meat
  • fish
  • poultry
  • many fortified breakfast cereals and bread products
  • fortified nutritional yeast products

Examples of foods rich in vitamin B9 include:

  • dark leafy vegetables, asparagus, broccoli
  • beef liver
  • fruit, especially citrus fruit
  • beans and nuts

To help reduce the risk of high or low neutrophil levels, people may want to try the following tips:

  • Try not to over-exercise or exercise beyond comfort levels.
  • Reduce stress levels and treat chronic or severe stress.
  • Seek medical attention for signs of infection, such as fever, weakness, fatigue, or pain, and treat infections exactly as prescribed.
  • Eat a nutritious, balanced diet.
  • Eat enough protein.
  • Treat chronic conditions, such as genetic or inflammatory conditions, exactly as prescribed.

However, people with only minor or mild changes in their neutrophil blood levels often show no symptoms and do not require treatment.

When neutrophil levels are higher or lower than usual for more than a short period, a doctor will order several tests to work out the underlying cause.

The outlook of neutropenia disorders depends on the cause of neutropenia and the organs involved. Serious infections occur in a significant number of people with neutropenia, and many people may require repeated hospital admission to help prevent infections and treat life threatening conditions.

Neutropenia due to chemotherapy or drugs may cause remission when the treatment is over.

Neutropenia, when left untreated, is associated with a high risk of death.

Having an appropriate number of neutrophils in the blood and bone marrow is crucial for your immune system to work correctly and help you heal from infection or injury.

Neutrophilia, when neutrophil levels are higher than usual, is often related to:

  • infection
  • illness
  • injury
  • physical or emotional stress
  • medication use
  • inflammatory conditions

Neutropenia, where neutrophil levels are lower than usual, is often related to:

  • severe or chronic infection
  • cancer
  • drug therapy
  • vitamin deficiency
  • genetic conditions

It is a good idea to have regular wellness checks at a doctor’s office. Anyone with concerns about their neutrophil level or any medical condition should talk with their healthcare professional.