What causes a low white blood cell count?

If a person has too many—or too few—white blood cells in the body, it may mean that there is a disorder of some kind. A white blood cell count of less than 4,000 cells per microliter of blood is considered low. Sometimes a low white blood cell count is something you are born with (a genetic condition), which may or may not be a cause for concern. A low white blood cell count is associated with certain conditions, including:

  • Cancer (caused by chemotherapy treatments)
  • Bone marrow disorders or damage
  • Autoimmune disorders (problems with the immune system in which the body attacks itself), such as lupus
  • Infections (including tuberculosis and HIV)
  • Immune system conditions
  • Crohn’s disease
  • Malnutrition
  • Radiation treatments for cancer
  • Rheumatoid arthritis
  • Vitamin deficiencies
  • Liver damage and/or enlarged spleen

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