White Blood Cell Count and Test Result

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

* The Content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.