All About Neutropenia

Author: Carolyn Vachani, MSN, RN
Last Reviewed: July 21, 2022

What are white blood cells?

A white blood cell (WBC) is one type of blood cell in the body. These cells are part of our immune system. Our immune system fights infection and protects our bodies from harmful bacteria, viruses and other foreign invaders. WBCs are made in the bone marrow. They are found throughout our blood and lymph systems. There are five types of white blood cells. Each has its own job in the immune system:

  • Neutrophils (50-70% of the WBCs).
  • Lymphocytes (T and B cells) (25-35%).
  • Monocytes (4-6%).
  • Basophils (0.4-1%).
  • Eosinophils (1-3%).

In order to check the number of these different white blood cells in your blood, your provider may order a Complete Blood Count (CBC) blood test with differential. Your provider may also check your “ANC” which is a total count of neutrophils. This article will focus on the role of neutrophils and what happens when their levels are low.

What is a neutrophil?

A mature neutrophil

  • Neutrophils make up the largest number of WBCs.
  • They are the "first responders" of our immune system.
  • They quickly go to the site of infection, taking in, and killing foreign particles.
  • They can be found in the pus of a wound and play a role in acute inflammation (redness, warmth, swelling, and pain).
  • Mature neutrophils are sometimes called "segs,” named for their segmented (broken up) nucleus.
  • Immature neutrophils are called "bands" because their nucleus appears banded.
  • These mature segs and immature bands together make up the “absolute neutrophil count”, or “ANC”.

What is neutropenia?

  • A normal ANC is between 2,500 and 5,000.
  • A low neutrophil count is called “neutropenia.” Neutropenia means an ANC of less than 1,500 but can be lower.

What causes neutropenia?

Neutropenia can be caused by:

  • A health issue such as cancer that affects the bone marrow or an immune disorder.
  • Cancer medications such as chemotherapy and targeted therapies.
  • Radiation therapy can damage the bone marrow that makes these blood cells, leading to neutropenia.
  • Other medications can also cause neutropenia such as anti-thyroid medicines, several types of antibiotics, and some blood pressure medicines and more.

Why do cancer therapies cause neutropenia?

Cancer therapies, such as chemotherapy, biotherapy, and radiation therapy, can cause neutropenia. These therapies cannot tell the difference between cancer cells and healthy cells. Most chemotherapies work by killing cells that divide quickly. Cancer cells divide quickly, but so do blood/bone marrow cells like WBC, hair follicles, and the cells that line the gastrointestinal (GI) tract (mouth, throat, stomach, and bowel). Damage to these normal cells causes the side effects of chemotherapy (low blood counts, hair loss, mouth sores, and diarrhea). Radiation damages blood cells by affecting the bone marrow production in the bones in the area of treatment.

Why is neutropenia important?

A low neutrophil count raises the risk of getting an infection. When a bacteria enters the body, there are not enough neutrophils to attack. There are levels of neutropenia, but the lower the ANC, the higher the risk of getting an infection.

Grades of Neutropenia

  • Mild Neutropenia: An ANC between 1,000 and 1,500. Minimal risk of infection.
  • Moderate Neutropenia: An ANC between 500 and 1,000. Moderate risk of infection.
  • Severe Neutropenia: An ANC less than 500. Severe risk of infection.

What is a nadir?

Nadir is a term you might hear your healthcare team use. Nadir is the point after treatment when your blood counts are at their lowest. This can include white blood cells, red blood cells, and/or platelets, depending on the type of treatment you received and your body's response to the treatment. This decrease in blood counts is also called “myelosuppression.”

Nadir often occurs 7-10 days after chemotherapy. Your blood counts will then slowly climb back before the next treatment. If your blood counts have not come back up enough, your healthcare team may delay your next therapy. Giving you more therapy with blood counts that are too low could make it very hard for your body to recover.

What can I do to avoid infection?

Hand washing, hand washing, hand washing! This is the number one way to prevent infection. This should include you and all other members of the household. If you are around small children, teach them to wash their hands, and make it their way to help you get better. Avoid large crowds, like the mall during the holidays. Avoid people you know are sick; this includes colds, viruses, or other infections. If they want to visit and are sick, tell them to call you instead. It is also a good idea to avoid people who live in a house with other people who are sick. For instance, Aunt Susie's three kids are sick, but she feels fine, so she's going to come for a visit. Err on the side of caution and tell her to stay home.

Even the best hand washers can get an infection, so you need to know the signs of an infection to look for. You may think of getting a high fever, redness, swelling, or pus as signs of an infection. These signs are caused by neutrophils and you don’t have enough neutrophils to cause these signs. When neutrophils and other blood counts are low, you must take even the most minor sign seriously and call your healthcare team right away, no matter the day or time. A temperature of 100.4°F (38°C) can be a sign of a very dangerous situation in a person on treatment. Make sure you know the number to call if you need to report a fever or other problem on a night or weekend.

Signs of Infection to Watch for:

  • Temperature > 100.4°F (38°C).
  • Shaking chills.
  • Cough, sore throat.
  • Burning when you pee (urinate).
  • New lower back pain.
  • Blood in pee (urine).
  • Diarrhea or loose stool.
  • Rash.
  • Redness, soreness around central line catheter, or a wound.

What can be done to prevent neutropenia?

Unfortunately, there is no vitamin we can take or food we can eat to prevent neutropenia. A group of medications, called growth factors, or colony-stimulating factors, can help prevent neutropenia or help shorten the length of time you are neutropenic. Your healthcare provider may prescribe one of these medications. There are a few growth factors available in the United States: filgrastim (Neupogen®), pegfilgrastim (Neulasta®), and sargramostim (Leukine®). These are manmade versions of a protein naturally produced in the body that helps you make more neutrophils.

These medications are given as a subcutaneous (SubQ) injection (a shot given just under the skin). These medications are started no earlier than 24 hours after chemotherapy. In the case of filgrastim and sargramostim, they are given once a day until after the nadir and the ANC returns to a normal level. In the case of pegfilgrastim, only one injection is required, given 24 hours after chemotherapy. There is also a version of pegfilgrastim (On-Pro) that is a patch put on your arm by your provider that automatically gives you the injection the next day at the correct time.

Why is it important to prevent neutropenia?

Your healthcare team has planned out the cancer therapies and/or radiation dose and schedule for your specific case. Neutropenia can cause delays in treatment and dose reductions (receiving a lower dose), which can make your treatment less effective. Studies show that for certain types of cancer, cancer therapies give the best long-term results when patients receive the full dose on time, every time. Preventing neutropenia gives you a better chance of sticking to your treatment schedule. And that is important for treating the cancer.

What else should I know?

Be an educated consumer! Ask your healthcare team about your blood counts and record them in a log. Know the signs of infection and who to notify if you develop any. If you experience neutropenia, ask about using a growth factor for future cycles of chemotherapy. And teach those around you how they can help to keep infection at bay (hint: wash your hands).

Other Resources

Blood counts log: print this log to keep track of your blood counts and treatments.

OncoLink Rx: learn about the medications you are receiving.

Neutropenia Tip Sheet: Here you will find helpful tips about infection and cancer-related neutropenia.


American Society of Clinical Oncology (ASCO). (2019). Neutropenia. Retrieved from

Coates, TD. (2022) Drug-Induced Neutropenia. UpToDate. Retrieved July 21, 2022 from

U.S. Department of Health and Human Services, National Institute of Health: National Cancer Institute. (2019). White Blood Cell. Retrieved from


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