White blood cells (WBC), also called leukocytes, are cells that exist in the blood and tissues. They help protect against infections and also have a role in inflammation, allergic responses, and protecting against cancer.
WBC count is a test included in a complete blood count (CBC), which is often used in the general evaluation of a person’s health. A health practitioner will consider the results of a WBC count together with results from other components of the CBC as well as a number of other factors.
What does the test result mean?
A high white blood cell count, called leukocytosis, may result from a number of conditions and diseases. Some examples include:
- Infections, most commonly caused by bacteria and some viruses
- Leukemia, myeloproliferative neoplasms
- Inflammation or inflammatory conditions such as rheumatoid arthritis, vasculitis or inflammatory bowel disease
- Conditions that result in tissue death (necrosis) such as trauma, burns, surgery or heart attack
- Allergic responses
A low white blood cell count, called leukopenia, can result from conditions such as:
- Bone marrow damage, such as toxin, chemotherapy or radiation therapy.
- Bone marrow disorders, such as myelodysplastic syndrome, vitamin B12 or folate deficiency.
- Lymphoma or other cancer that has spread to the bone marrow.
- Autoimmune disorders—the body attacks and destroys its own WBCs (e.g., lupus)
- Dietary deficiencies
- Overwhelming infections (e.g., sepsis)
- Diseases of the immune system, such as HIV.
Keywords: white blood cell count; WBC count