A white blood cell (WBC) count is a test that measures the number of white blood cells in your body. This test is often included with a complete blood count (CBC). The term “white blood cell count” is also used more generally to refer to the number of white blood cells in your body.
There are several types of white blood cells, and your blood usually contains a percentage of each type. Sometimes, however, your white blood cell count can fall or rise out of the healthy range.
WBCs, also called leukocytes, are an important part of the immune system. These cells help fight infections by attacking bacteria, viruses, and germs that invade the body.
White blood cells originate in the bone marrow but circulate throughout the bloodstream. There are five major types of white blood cells:
The normal percentages of the types of WBCs in your overall count are usually in these ranges, according to the Leukemia & Lymphoma Society (LLS): (this may vary with your testing lab, please check your own lab)
|Type of WBC||Normal percentage of overall WBC count|
|neutrophil||55 to 73 percent|
|lymphocyte||20 to 40 percent|
|eosinophil||1 to 4 percent|
|monocyte||2 to 8 percent|
|basophil||0.5 to 1 percent|
Higher or lower numbers of WBCs than normal can be a sign of an underlying condition.
Having a higher or lower percentage of a certain type of WBC can also be a sign of an underlying condition.