Neutropenia is characterized by a significant reduction in neutrophils, a type of white blood cell that is an essential first line of defense against infections. The main complication of neutropenia is an increased risk of infection.

Neutrophils are made in the bone marrow. They are short-lived cells that travel extensively throughout the body and can enter tissues other cells cannot.

Most commonly, cancer patients develop neutropenia due to chemotherapy. The drugs involved destroy the neutrophils along with the cancer cells they are designed to kill.

In this article, we will discuss the causes, symptoms, and treatments of neutropenia.

Fast facts on neutropenia

Here are some key points about neutropenia. More detail and supporting information is in the main article.

  • In health, neutrophils are the most abundant type of white blood cell.
  • One of the most common causes of neutropenia is chemotherapy.
  • Often, there are no particular symptoms other than a heightened risk of infection.
  • Febrile neutropenia is regarded as a medical emergency.
  • Individuals with neutropenia must take extra precautions to avoid infection.

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Neutropenia describes a reduction in neutrophils.

Neutropenia is a condition where there are abnormally low levels of neutrophils in the blood supply. Neutrophils are an important type of white blood cell, vital for fighting off pathogens, particularly bacterial infections.

In adults, a count of 1,500 neutrophils per microliter of blood or less is considered to be neutropenia, with any count below 500 per microliter of blood regarded as a severe case.

In severe cases, even bacteria that are normally present in the mouth, skin, and gut can cause serious infections.

Neutropenia can be due to a decrease in neutrophil production, accelerated usage of neutrophils, increased destruction of neutrophils, or a combination of all three factors.

Neutropenia can be temporary (acute) or long-lasting (chronic). The condition is also split into congenital (present from birth) and acquired neutropenia (develops later in life).

There is a range of neutropenias, including:

Cyclic neutropenia: This is a rare congenital syndrome causing fluctuations in neutrophil numbers, it affects an estimated 1 in 1,000,000 people.

Kostmann's syndrome: This is a genetic disorder where neutrophils are produced at lower levels. People with Kostmann's syndrome are prone to infections from an early age.

Chronic idiopathic neutropenia: This is a relatively common version of neutropenia, predominantly affecting women.

Myelokathexis: This is a condition in which neutrophils fail to move from the bone marrow (where they are created) to the bloodstream.

Autoimmune neutropenia: This occurs when an individual's immune system attacks and destroys neutrophils.

Shwachman-Diamond syndrome: This is a rare genetic disorder with multiple effects including dwarfism, problems with the pancreas, and a low neutrophil count.

Isoimmune neonatal neutropenia: This is a condition where a mother's antibodies cross the placenta and attack the developing fetus' neutrophils. This condition generally resolves itself within 2 months of life. It can be asymptomatic or result in sepsis.

Neutrophils are produced in the bone marrow at the center of larger bones. Anything that disrupts this process can cause neutropenia.

Most commonly, neutropenia is caused by chemotherapy for cancer. In fact, around half of cancer patients undergoing chemotherapy will experience some level of neutropenia.

Other potential causes of neutropenia include:

  • leukemia
  • certain medications, including antibiotics and drugs for high blood pressure, psychiatric disorders, and epilepsy.
  • Barth syndrome, a genetic disorder affecting multiple systems
  • myelodysplastic syndromes, which are a group of disorders characterized by dysfunctional blood cells due to problems with bone marrow production
  • myelofibrosis, a rare bone marrow problem, also known as osteomyelofibrosis
  • alcohol dependency
  • vitamin deficiencies, most commonly vitamin B12, folate, and copper deficiency.
  • sepsis, an infection of the bloodstream that uses up neutrophils quicker than they can be produced.
  • Pearson syndrome
  • certain infections, including hepatitis A, B, and C, HIV/AIDS, malaria, tuberculosis, dengue fever, and Lyme disease.
  • hypersplenism, or an enlarged spleen

Some autoimmune conditions can target neutrophils, reducing their number. These conditions include:

Premature babies are more likely to be born with neutropenia than babies born near their due date. The condition affects 6 to 8 percent of newborns in neonatal intensive care units. As a general rule, the smaller the baby, the more likely they are to have neutropenia.

Medical News Today asked a consultant hematologist why chemotherapy's attack on neutrophils is so significant, compared with the destruction of other types of white blood cell. He said:

"Chemotherapy affects all cells of the granulocytic lineage, but it is the neutrophils that are most important in acute bacterial infections, and so we are most vigilant when they are low.

When someone is neutropenic, severe infections can develop rapidly and become overwhelming in the space of minutes to hours. In contrast, having too few basophils or eosinophils will not expose you to much harm in the short term."

Dr. Joel Newman MB BS, BSc (Hons), MRCP, FRCPath

Neutropenia itself does not present any symptoms. Often it is spotted during routine blood tests or tests for another condition. For this reason and others, patients undergoing chemotherapy - who are most at risk from the condition - will have regular blood tests.

The most serious concern with neutropenia is contracting an infection, which can easily spread throughout the body without adequate neutrophil numbers to control it.

Signs of infection include:

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Infections must be treated as soon as they are recognized.
  • high fever or low temperature
  • chills and sweating
  • flu-like symptoms
  • malaise
  • mucositis, a painful inflammation and ulceration of the mucous membranes of the digestive tract
  • abdominal pains
  • diarrhea and vomiting
  • changes in mental state
  • sore throat, toothache, or mouth sores
  • pain near the anus
  • burning sensation when urinating
  • increased urination
  • coughing
  • trouble breathing
  • redness or swelling around wounds
  • unusual vaginal discharge

If an infection takes hold, there is a risk of febrile neutropenia, also referred to as neutropenic sepsis. This condition is a medical emergency and occurs most commonly in cancer patients undergoing chemotherapy. Mortality rates range from 2 to 21 percent.

Febrile neutropenia is defined as:

  • a fever above 101 Fahrenheit or greater than 100.4 Fahrenheit for 1 hour or more
  • an absolute neutrophil count of 1,500 cells per microliter or less

It is vital that an infection is treated immediately in a patient with neutropenia.

The treatment of neutropenia will depend on the underlying reason for the disorder. Medical treatments to help reduce the impact of neutropenia include:

Granulocyte-colony stimulating factor (G-CSF): This is a glycoprotein that stimulates the bone marrow to produce neutrophils and other granulocytes and releases them into the bloodstream. The most commonly used version of G-CSF is a drug called filgrastim.

Granulocyte-macrophage colony-stimulating factor (GM-CSF): Naturally produced glycoprotein carries out a similar role to G-CSF. Both promote neutrophil recovery after chemotherapy.

Antibiotics: Prophylactic antibiotics may sometimes be given to reduce the likelihood of infection. They are often given at the point in time when the neutrophil count is likely to be lowest.

Some basic lifestyle precautions are necessary for individuals with neutropenia. They should remove as many risks of infection from their daily routine as possible.

Lifestyle precautions for people with neutropenia include:

  • cleaning hands regularly, especially after using the toilet
  • avoiding crowds and people who are ill
  • not sharing personal items including toothbrushes, drinking cups, cutlery, or food
  • bathing or showering daily
  • cooking meat and eggs thoroughly
  • not buying food in damaged packages
  • cleaning the fridge thoroughly and not overfilling - doing so can raise the temperature
  • carefully washing any raw fruit or vegetables or avoiding completely
  • avoiding direct contact with pet waste and washing hands after handling any animals
  • wearing gloves when gardening
  • using a soft toothbrush
  • using an electric shaver rather than a razor
  • cleaning any wounds with warm water and soap and using antiseptic to clean the site
  • wearing shoes outdoors
  • not squeezing spots or picking scabs
  • keeping surfaces clean
  • getting the flu shot as soon as it becomes available