Neutropenia: The Basics
What are white blood cells?
White blood cells (WBC) are just one piece of the very complex immune system in our bodies. This system is responsible for fighting infection and protecting our bodies from harmful bacteria, viruses and other foreign invaders. There are five different types of white blood cells, each with its own purpose in the immune system: neutrophils (accounting for 50-70% of the WBCs), lymphocytes (25-35%), monocytes (4-6%), basophils (0.4-1%), and eosinophils (1-3%). A WBC count with differential is the blood test that reports the numbers of these cells in the blood.
What are neutrophils and neutropenia?
Neutrophils make up the majority of WBCs and are formed in the bone marrow. They are the "first responders" and quickly appear at the site of infection, ingesting and destroying foreign particles. They can be found in the pus of a wound and play a role in acute inflammation (redness, warmth, swelling, and pain). A normal neutrophil count (also called absolute neutrophil count or ANC) is between 2500 and 5000. A low neutrophil count is known as neutropenia. Neutropenia can be caused by a congenital or inherited disorder, or can be a side effect of a medication or radiation therapy. Chemotherapy medications are the most common cause of neutropenia, but other medications can also cause neutropenia, including (but not limited to): sulfonamides (Bactrim), allopurinol, ibuprofen, indomethasone, several types of antibiotics, blood pressure and anti-seizure medications. For the purposes of this article, we will only discuss neutropenia caused by cancer therapies.
Mature neutrophils are sometimes called "segs", named for their segmented nucleus. Immature neutrophils are called "bands" because their nucleus appears banded. These 2 counts together make up the absolute neutrophil count, or ANC.
A mature neutrophil
Cancer therapies, including chemotherapy, biotherapy, and radiation therapy, can cause neutropenia. This is because these therapies are unable to tell the difference between cancer cells and healthy cells. Most chemotherapies work by killing rapidly dividing cells. Cancer cells divide rapidly, but so do blood / bone marrow cells, hair follicles, and the cells that line the gastrointestinal tract (mouth, throat, stomach, and bowel). Damage to these normal cells leads to the side effects we see with chemotherapy (low blood counts, hair loss, mouth sores, and diarrhea). Radiation damages blood cells by affecting the marrow production in the bones in the area of treatment.
Why is neutropenia important?
A low neutrophil count greatly increases the risk of developing an infection because your usual mechanism to respond to infection (neutrophils) is not available. There are various levels of neutropenia, but the lower the ANC, the higher the risk of developing infection.
Grades of Neutropenia
- An ANC between 1000 and 1500 is considered mild neutropenia (causing minimal risk of infection)
- An ANC between 500 and 1000 is considered moderate neutropenia (causing moderate risk of infection)
- An ANC less than 500 is considered severe neutropenia (causing a severe risk of infection)
What is a nadir?
Nadir is a term used by the healthcare team to describe 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. With chemotherapy, this often occurs 7-10 days after treatment. Your blood counts will then slowly climb back to an acceptable level before the next treatment. If your blood counts have not gotten back to an acceptable level, your healthcare team will hold off on giving you more therapy. Giving you more therapy with blood counts that are too low could make it very difficult for your body to recuperate.
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 participate and 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 must visit, tell them to make it a phone visit. 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.
Now, even the best hand washers can get an infection, so you need to be on the lookout for the signs. We often think of developing a high fever, redness, swelling, or pus as signs of an infection, but remember these signs are the job of the neutrophils and they are on vacation! When your counts are low, you must take even the slightest sign as serious and notify your healthcare team- even if it is 3 am on Saturday night. A temperature of 100.5 can be a sign of an extremely dangerous situation in a patient on treatment, so don't take the chance. 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
- Shaking chills
- Cough, Sore throat
- Burning with urination New lower back pain
- Blood in urine
- Diarrhea (worsening)
- Redness, soreness around central line catheter or a wound
What can be done to prevent neutropenia?
Unfortunately, there is no magic 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 make the time you are neutropenic shorter. 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 stimulates neutrophil production. These medications are given as a subcutaneous injection (just under the skin) and are started no sooner than 24 hours after chemotherapy. In the case of filgrastim and sargramostim, they are given once a day until the nadir point passes and the ANC returns to a normal level. In the case of pegfilgrastim, only one injection is required, given 24 hours after chemotherapy.
Why is it important to prevent neutropenia?
Your healthcare team has determined the chemotherapy and/or radiation dose and schedule to produce the best opportunity for success in your case. Neutropenia can lead to delays in treatment and dose reductions, which can make your chemotherapy less effective. Studies show that for certain types of cancer, chemotherapy produces the best long-term results when patients receive the full dose on time, every time. With good recovery of your white blood cell count, you may have a better chance of sticking to your treatment schedule. And most healthcare providers agree that doing so is the first step to success.
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).
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 from our Oncology Nurse Educator about infection and cancer related neutropenia. You will find information that explains what neutropenia is, why it happens, how it is treated, and what you can do to prevent yourself from developing it.
Neutropenia Medications: Find out about medications which may be used to help infection and cancer related neutropenia or to shorten the duration of neutropenia in some cancer patients receiving chemotherapy and radiation therapy.