What is neutropenia?

Neutropenia is a low number of neutrophils. Neutrophils are a type of white blood cell, and the National Cancer Institute describes them as the ones that "help your body to fight infection." When they run low, ordinary germs that your body would normally clear without you noticing can turn dangerous.

The number behind the word

The measurement is the neutrophil count, sometimes called the absolute neutrophil count or ANC. It comes off the same complete blood count your team already draws.

MedlinePlus, the patient library of the National Library of Medicine, gives the general cut-offs for adults:

• Fewer than 1,000 neutrophils in a microliter of blood is, in general, neutropenia.
• Fewer than 500 is called severe neutropenia. At that level, MedlinePlus says, "even the bacteria normally living in a person's mouth, skin, and gut can cause serious infections.".

MedlinePlus suggests asking for your white blood cell count and, specifically, your neutrophil count when your blood is tested. "Your counts are low" is less useful than the number.

Why chemotherapy causes it

Chemotherapy targets cells that divide quickly. Cancer cells do, but so do the cells in your bone marrow that produce blood. That is why the risk moves in a predictable rhythm rather than staying flat. NCI notes that "During chemotherapy, there will be times in your treatment cycle when the number of white blood cells (called neutrophils) is particularly low and you are at increased risk of infection." Ask your nurse which days of your cycle are the low point. That is the week to be careful.

Why it is treated as an emergency

CDC says that if you get a fever during chemotherapy, "it's a medical emergency," and that an infection during chemotherapy can be life-threatening. NCI says infections during cancer treatment "can be life threatening and require urgent medical attention."

CDC's threshold for calling right away is a fever of 100.4 °F (38 °C) or higher. NCI lists other signs to report. They are chills, cough or sore throat, diarrhea, ear pain, headache or sinus pain, a stiff or sore neck, skin rash, sores or a white coating in your mouth, swelling or redness where a catheter enters your body, and urine that is bloody or cloudy or painful to pass. If you cannot reach your team, go to the emergency department.

What actually helps

Some of it is prevention. NCI advises frequent handwashing, careful cleaning around catheter sites, avoiding crowds and people who are sick, following food safety rules, and eating well-cooked food. NCI also notes that "medicine may sometimes be given to help prevent infection or to increase the number of white blood cells." Ask your team whether that applies to you.

The rest is logistics. Keep a working thermometer somewhere you can find it half asleep, and keep the 24-hour oncology number with it. If you end up in an emergency room, open with this sentence: "I am on chemotherapy and I have a fever." It tells the staff right away why the fever matters.