What causes absolute neutrophils to be low

Neutropenia is when a person has a low level of neutrophils. Neutrophils are a type of white blood cell. All white blood cells help the body fight infection. Neutrophils fight infection by destroying harmful bacteria and fungi (yeast) that invade the body. Neutrophils are made in the bone marrow. Bone marrow is the spongy tissue found in larger bones such as the pelvis, vertebrae, and ribs.

Half of people with cancer who are receiving chemotherapy have some level of neutropenia. It is a common side effect in people with leukemia. People who have neutropenia have a higher risk of getting serious infections. This is because they do not have enough neutrophils to kill organisms that cause infection. People with severe or long-lasting neutropenia are most likely to develop an infection.

Signs and symptoms of neutropenia

Neutropenia itself may not cause any symptoms. People usually find out they have neutropenia from a blood test or when they get an infection. Some people will feel more tired when they have neutropenia. Your doctor will schedule regular blood tests to look for neutropenia and other blood-related side effects of chemotherapy.

For people with neutropenia, even a minor infection can quickly become serious. Talk with your health care team right away if you have any of these signs of infection:

• A fever, which is a temperature of 100.5°F (38°C) or higher

• Chills or sweating

• Sore throat, sores in the mouth, or a toothache

• Abdominal pain

• Pain near the anus

• Pain or burning when urinating, or urinating often

• Diarrhea or sores around the anus

• A cough or shortness of breath

• Any redness, swelling, or pain (especially around a cut, wound, or catheter)

• Unusual vaginal discharge or itching

Causes of neutropenia

Several things related to cancer and its treatment can cause a low level of neutrophils, including:

• Some types of chemotherapy

• Cancers that affect the bone marrow directly, such as leukemia, lymphoma, and multiple myeloma

• Cancer that has spread

• Radiation therapy to several parts of the body or to bones in the pelvis, legs, chest, or abdomen

Some people with cancer are more likely to develop neutropenia, including:

• People who are age 70 or older

• People with a lowered immune system from other causes, such as having HIV or an organ transplant

Chemotherapy and neutrophils

The timing of the drop in neutrophil levels is based on the type or dose of chemotherapy.

• Neutrophil counts generally start to drop about a week after each round of chemotherapy begins.

• Neutrophil levels reach a low point about 7 to 14 days after treatment. This is called the nadir. At this point, you are most likely to develop an infection.

• Your neutrophil count then starts to rise again. This is because your bone marrow restarts normal production of neutrophils. But it may take 3 to 4 weeks to reach a normal level again.

• When your neutrophil level returns to normal, you are ready for the next round of chemotherapy.

Managing and treating neutropenia

An important part of cancer care is relieving the side effects of treatment. This is called palliative care or supportive care. Talk with your health care team about any symptoms you have or any changes in symptoms.

While taking chemotherapy, sometimes your neutrophil level does not return to normal fast enough. Or you develop neutropenia. In this case, your doctor may take certain precautions, including:

• Delaying the next round or lower the dose of chemotherapy.

• Recommending antibiotics during longer periods of neutropenia to prevent infections.

• If you have neutropenia with a fever, your doctor may give you medications called white blood cell growth factors. These drugs help the body make more white blood cells. Read more about ASCO’s guideline on white blood cell growth factors.

If you have neutropenia, practice good personal hygiene to lower your risk of infection. This includes washing your hands regularly and staying away from people who are sick.

A lowered level of immunity is called immunosuppression. Certain diseases, including cancer, and certain treatments, including chemotherapy and radiation therapy, can cause some people to have immunosuppression. This is usually referred to as having a low white blood cell count, but you might hear other words to describe it too.

What is neutropenia?

Neutropenia is defined as a lower than normal number of neutrophils (a type of white blood cells). White blood cells are part of the immune system. There are different types of white blood cells, and they each have a key role in the body’s defense against germs:

• Neutrophils
• Lymphocytes (which include T-lymphocytes and B-lymphocytes)
• Monocytes
• Macrophages

Neutrophils are key infection-fighters

Neutrophils form a very important defense against most types of infection. Normally, most of our white blood cells are neutrophils. In patients with cancer, neutropenia is usually caused by treatment. When looking at your risk of getting an infection, doctors look at the number of neutrophils you have.

If your neutrophil count is low, the doctor may say you are neutropenic. For most people with cancer, having a low neutrophil count is the biggest risk factor for getting a serious infection. Ask your doctor if your cancer treatment will cause your neutrophil count to drop.

Lymphocytes can mark, signal, and destroy germs

Some treatments, most often those given during a bone marrow (stem cell) transplant, can cause a shortage of lymphocytes. B and T lymphocytes help fight viruses, but have different jobs:

• B-lymphocytes make special proteins called antibodies that recognize and kill certain germs. They also can mark germs to be destroyed by other cells.
• T-lymphocytes make signaling substances called cytokines that tell other cells what to do. They also destroy cells infected by viruses.

Monocytes and macrophages help recognize invaders

• They help lymphocytes recognize germs.
• They can surround and digest germs that have been coated by antibodies (the proteins made by B-lymphocytes).
• They help fight bacteria, fungi, and parasites.

What is an absolute neutrophil count (ANC)?

You might hear your doctor or nurse talk about your absolute neutrophil count or ANC. This is the number of neutrophils you have in a certain amount of blood. Your health care team will use your ANC to get an idea of how well your immune system might work during treatment. A blood test called a complete blood count (CBC) is used to see how well your immune system is working. It measures your white blood cells (WBCs), and your cancer care team is able to figure out your ANC from your WBC count. Your cancer care team will use your ANC to get an idea of how your immune system is affected by treatment and how well it is working to protect you from infection.

As the ANC gets lower, the usual signs of infection, such as fever, pus, pain, swelling, and redness, may not show up when an infection starts. This is because these signs are caused by neutrophils fighting off germs, and if you don’t have enough neutrophils to fight infection, you won't produce the signs. This can make it hard to know if you have an infection. The good thing is that another WBC, called the monocyte, can still cause signs of infection in a person who has neutropenia. Sometimes in people with severe neutropenia a fever may be the only sign of an infection. The lower your ANC is and the longer it stays low, the higher your risk of infection will be.

Ask your doctor if your cancer treatment might cause your neutrophil count to drop. Your cancer care team will help you find the ANC on your lab results and can help explain more about it.

What can cause or increase the risk for neutropenia?

• Some types of chemotherapy
• Radiation therapy
• Bone marrow or stem cell transplant  
• Steroids

Symptoms of neutropenia

• Fever
• Chills
• Mouth sores
• Cough
• Difficulty breathing
• Abdominal or rectal pain

Problems neutropenia might cause

• Increased risk for infection
• In a person with a healthy immune system, the usual signs of infection may include fever, pus, pain, swelling, and redness. As the ANC gets lower, many of these signs may not show up when an infection starts. This is because these signs are caused by neutrophils fighting off germs, and you don’t have enough neutrophils to produce the signs.
• Your cancer care team may have to delay your treatment or reduce your dose to prevent further neutropenia

Treatment of neutropenia

Treatment may include one or a combination of the following:

• Myeloid growth factors: These are proteins that stimulate the bone marrow to produce more white blood cells to help the body fight infections. They are also known as growth factors or colony-stimulating factors (CSFs).  Examples of growth factors include filgrastim (Neupogen, other names), tbo-filgrastim (Granix), pegfilgrastim (Neulasta, other names), and eflapegrastim (Rolvedon).
• Antibiotics may be given in certain instances to help prevent infection.
• Cancer treatment may be delayed to give your body enough time to make more white blood cells and recover your ANC.

Talk to your cancer care team about what to watch for. Call your doctor if you have a fever (your cancer care team will let you know what temperature they consider a fever) or any other symptoms of neutropenia.

Should I be worried if my neutrophils are low?

What does a low level of absolute neutrophils mean?

What diseases cause low neutrophils?

How can I raise my absolute neutrophil count?