Understanding White Blood Cell Count – Normal, High, & Low

High white blood cell count

A high blood cell count is also known as leukocytosis, and it is typically diagnosed when levels are higher than 11,000/μL. The white blood cells are produced by the bone marrow when the immune system is stimulated in some way. They are cleared from the blood by the spleen, and these cells are very important for inflammation. Thus, a high blood cell count usually points to one of the following causes:

  • Infections: A common cause of high white blood cell count, usually a bacterial infection.
  • Leukemia and lymphoma: They are cancers related to the immune system, and activate the production of new white blood cells by genetic aberrations and through the activation of oncogenes.
  • Extensive tissue damage: In trauma, extensive wounds or burns, the immune system becomes activated, and white blood cells are typically found in higher levels.
  • Acute or chronic inflammation: In autoimmune disease, allergies, and other inflammatory problems, white blood cells are usually higher than normal or borderline.
  • Cigarette smoking and drugs: Cigarette smoking triggers inflammation and stimulates the production of white blood cells. Similarly, patients who are using corticosteroids heparin, lithium, albuterol, and similar drugs, are likely to find a higher level of white blood cells in their complete blood count.

Cases of high white blood cell count are usually investigated by considering the proportion of white blood cells. This will give a very important clue in cases of infectious diseases. When there’s a higher proportion of neutrophils, bacterial infections are the likely cause. In cases of high levels of lymphocytes, the viral disease is commonly suspected. Higher eosinophil count typically points out to fungi or parasitic infections, and a higher count of basophils is associated with inflammation and allergies.