A reduced number of blood cells in circulation is a common side effect of chemotherapy. Blood is composed of three basic blood cell types: red blood cells, white blood cells, and platelets. Blood cells are produced in the bone marrow and regularly released into circulation. Chemotherapy destroys rapidly dividing cells, a characteristic of cancer cells. However, bone marrow cells also divide rapidly and are frequently damaged by chemotherapy. Blood counts are monitored with a laboratory test called a Complete Blood Count (CBC). The best way to treat low blood counts is to prevent them before they occur. This can be accomplished with the administration of blood cell growth factors. In some circumstances, blood transfusions may also be necessary.

What are low blood counts?

A blood count is a measurement of the number of blood cells an individual has in circulation based on laboratory evaluation of a blood sample. Blood is composed of three basic blood cell types: red blood cells, white blood cells, and platelets. You should have billions of these blood cells circulating throughout your body. However, certain circumstances may cause you to have fewer cells than is considered normal, a condition which is called “low blood counts”. The laboratory test that is conducted to measure the number of blood cells is called a complete blood count, or CBC.

What causes low blood counts?

The most common reason cancer patients experience low blood counts is as a side effect of chemotherapy. Chemotherapy involves the use of drugs to destroy cancer cells. Chemotherapy works by destroying cells that grow rapidly, a characteristic of cancer cells. Unfortunately, chemotherapy also affects normal cells that grow rapidly, such as cells in the bone marrow that produce red blood cells, white blood cells, and platelets.

What are the symptoms of low blood counts?

Your symptoms will depend on which types of blood cells are low. Common symptoms of the different types of low blood cell counts are listed in table 1.

Table 1 Common Symptoms of Low Blood Counts

Low red blood cells Low white blood cells Low platelets
Fatigue or tiredness Infection Excessive bruising
Trouble breathing Fever Excessive bleeding
Rapid heartrate   Nosebleeds
Difficulty staying warm    
Pale skin    

Why is it important to monitor blood counts?

It is important to monitor for low blood cell count because this condition may:
  • Increase your risk of unpleasant and sometimes life-threatening side effects, such as fatigue, infection, and/or bleeding.
  • Disrupt delivery of your cancer treatment, resulting in a change to the planned dose and time.