Neutropenia is a condition caused by lower-than-normal amounts of neutrophils, a type of white blood cell. Neutrophils fight infection in the body by killing harmful bacteria and other blood-borne pathogens. The most common cause of neutropenia during breast cancer treatment is chemotherapy, though other types of cancer medicine can also cause it. Chemotherapy can cause neutropenia because it kills rapidly dividing cells, such as cancer cells. It can also affect other quickly dividing cells in our bodies, including white blood cells, red blood cells, and platelets. When chemotherapy destroys too many white blood cells, neutropenia occurs.

Throughout the course of a medical diagnosis, members of your health care team will order different laboratory blood tests. Many times, these laboratory blood tests will be repeated throughout the diagnosis, treatment, follow-up, and continuing care. Each medical diagnosis and treatment has specific factors that are required to be monitored. When it comes to the results of these tests and what counts are normal or not, it is important to know that “normal” ranges simply reflect average values in a population. It is common for some tests to be slightly outside of the “normal range” (low or high) without consequence and your clinicians can guide you with respect to their relevance.