Neutrophils are a type of white blood cell that is part of the immune system of the body. They are the most common form of white blood cells and play an important part in the body’s defense against bacterial and fungal diseases. Infections, injuries, pharmacological treatments, hereditary disorders, and stress can cause neutrophil numbers to rise or fall. When a person is sick or injured, the number of neutrophils in their blood increases to aid healing.

If an individual has a lengthy infection, cancer, an autoimmune illness, or is on certain drugs, neutrophil numbers may fall.

The body produces neutrophils in the bone marrow and account for 50-70% of all white blood cells in the bloodstream. An adult’s circulation typically contains between 4,500 and 11,000 white blood cells per millimeter cubed (mm3).

When the body is infected or there is another source of inflammation, specific molecules signal mature neutrophils, causing them to leave the bone marrow and move through the bloodstream to the place of need.

Band cells are immature neutrophils produced by your body while it is fighting an infection or inflammation. Bandemia is defined as an excess of band cells in the blood. When this happens, it’s usually an indicator of an infection or inflammation.

Function Of Neutrophils

• Neutrophils play a key role in the innate immune response, the body’s initial line of defense against infection. They are in charge of phagocytosis, which is the process by which they absorb and eliminate invading microbes like bacteria and fungi.
• Neutrophils are rapid in responding to infections or tissue damage. Within minutes, they can travel through blood vessels to the site of infection or inflammation. Their quick response aids in the containment and control of infection spread.
• Neutrophils have a relatively limited lifespan, which normally ranges from a few hours to a few days. They undergo programmed cell death after fulfilling their phagocytic activity and are eventually removed by the body’s immune system.
• Neutrophils release antimicrobial compounds to kill and neutralize infections. These chemicals include enzymes, reactive oxygen species, and antimicrobial peptides. These compounds aid in the eradication of bacteria and other microbes.

• Neutrophils play an extensive role in the body’s inflammatory response. Chemical signals emitted by wounded tissues or immune cells attract them to the location of the inflammation. Neutrophils send out extra chemical signals that attract other immune cells, boost the immunological response, and aid tissue healing.

A complete blood count (CBC) test frequently includes the evaluation of neutrophil numbers and other white blood cell counts. Abnormal neutrophil levels can indicate infections, inflammatory disorders, or other underlying health concerns. 

Causes Of High Or Low Neutrophil Levels

There are numerous reasons why a person’s neutrophil count may be higher or lower.

High levels

Neutrophophilic leukocytosis, commonly known as neutrophilia, is characterized by an excessively high amount of neutrophils in the blood.

Neutrophil levels typically rise as a result of infections or injuries. However, neutrophil blood levels may increase as a result of various drugs, including corticosteroids, beta-2 agonists, and epinephrine

a few cancers

• physical or psychological strain
• Accidents or surgery
• consuming tobacco
• Pregnancy
• being overweight
• Down syndrome (a hereditary condition).
• Surgery to remove the spleen

Some inflammatory disorders might raise neutrophil counts as well. These include rheumatoid arthritis, inflammatory bowel disease, hepatitis, and vasculitis.

Low levels

Neutropenia is defined as an unusually low level of neutrophils in the blood.

When the body uses immune cells quicker than it makes them, or the bone marrow does not manufacture them correctly, neutrophil blood levels fall.

A splenic enlargement may also result in a decrease in neutrophil counts. This is due to the spleen’s ability to trap and destroy neutrophils and other blood cells.

The following situations and procedures cause the body to consume neutrophils too quickly:

• Bacterial infections that are severe or chronic
• Allergic reactions
• Certain pharmaceutical therapies
• Autoimmune conditions

The following are some specific situations, procedures, and medicines that inhibit neutrophil production:

• Cancer
• Infections caused by viruses, such as influenza
• Infections caused by bacteria, such as tuberculosis
• Myelofibrosis is a bone marrow scarring condition.
• lack of vitamin B12
• Radiation treatment using bone marrow
• Phenytoin with sulfa medications
• Chemotherapeutic drugs
• Benzenes and insecticides are examples of toxins.
• When bone marrow is unable to produce enough blood cells (Aplastic anemia)
• severe congenital neutropenia, a set of conditions in which neutrophils fail to mature
• cyclic neutropenia, in which cell levels fluctuate
• Chronic benign neutropenia, characterized by low cell counts for no obvious reason

Testing

A complete blood count (CBC) with differential, identifying distinct groupings of white blood cells, can help doctors detect changes in neutrophil counts.

A doctor may order a CBC test if a patient is having signs of infection, chronic sickness, or injury, such as fever, pain, or weariness. A nurse or technician will take a little blood sample from the arm and submit it for testing.

If the initial test reveals a higher or lower-than-expected amount of white blood cells, the doctor will likely redo the test to verify the results. If the preliminary findings are verified, a doctor will conduct a physical examination, ask questions about the individual’s lifestyle, and check their medical history.

If no obvious cause for the alterations in white blood cell levels is identified, the doctor may order further detailed tests. CT scans, blood cultures, urine sample analysis, and a chest X-ray are all options.

Following a blood test, professionals will look for certain white blood cells, such as immature neutrophils known as myeloblasts. These cells come from the bone marrow and mature in the blood rather than the bone marrow after an infection or chronic disease.

If myeloblasts or other white blood cells are found in high concentrations in the blood, the doctor will ask for a bone marrow sample.

Interpreting The Results

Changes in neutrophil numbers are frequently indicative of larger changes in white blood cell counts.

The proportion and amount of white blood cells in the bloodstream varies with age and other events such as pregnancy. While everyone’s usual range is slightly different, the following are some regularly used ranges:

Newborn	13,000–38,000 per mm3
Infant 2 weeks of age	5,000–20,000 per mm3
Adult	4,500–11,000 per mm3
Pregnant female (third trimester)	5,800–13,200 per mm3

A white blood cell blood count of more than 11,000 per mm3 in people who are not pregnant is considered high. Neutrophilic leukocytosis develops if a person’s blood contains more than 7,000 mature neutrophils per mm3.

In human blood, the lower blood level limit for neutrophils is 1,500 per mm3. Neutropenia occurs when a person’s neutrophil numbers are low. The lesser the number of neutrophils in the blood, the more serious the neutropenia. Neutropenia levels are as follows:

Mild neutropenia	1,000–1,500 per mm3
Moderate neutropenia	500–999 per mm3
Severe neutropenia	below 499 per mm3

Minor fluctuations in neutrophil or white blood cell numbers are usually not a cause for concern as long as they are transient. A high white blood cell count frequently indicates that the body responds to an infection, injury, or stress.

Some persons have lower natural levels of white blood cells and neutrophils than others. A variety of circumstances, including congenital disorders, can contribute to this.

A doctor will prescribe tests to discover the cause if neutrophil or white blood cell levels are drastically altered for no obvious reason or remain elevated or reduced.

Extremely high or low numbers of white blood cells frequently necessitate immediate treatment and monitoring.

Takeaway

Neutrophils are a type of white blood cell (WBC) that play an important role in infection resistance. The quantity of neutrophils in your blood might fluctuate due to a variety of causes, such as illness, stress, chemotherapy treatment, or nutritional deficits.

Your neutrophil counts may be elevated in some instances. This is referred to as neutrophilia. In the case of neutropenia, the level may be dangerously low. It is critical to seek the advice of a healthcare professional for the proper interpretation of test results and management of any connected conditions.

Frequently Asked Questions

How can I boost my neutrophil count?

If you have a low neutrophil count, you can try to boost it by developing an action plan with your doctor. They may suggest:

Changing the chemotherapeutic dosage or timing.

Getting a transfusion of white blood cells.

Any medicine that causes a low white blood cell count should be discontinued.

Taking antibiotics or medicines that stimulate the formation of white blood cells.

Does neutropenia cause weariness?

Yes, a low neutrophil count is linked to weariness. This may put you at a heightened risk of infections.

How can I lower my neutrophil count?

Neutrophils naturally increase to combat infection, but if your count is higher than normal, your healthcare professional will find and treat any infection or medication reaction that may be the cause. Antibiotics are typically used to treat infections.

Is COVID-19 associated with an increase in neutrophils?

Yes. COVID-19 stimulates the immune system to create more white blood cells. Doctors believe those who produce an abnormally high number of neutrophils may be predisposed to more severe COVID symptoms.