White Blood Count (WBC) Test
A white blood count (WBC) measures the number of white blood cells in your blood. These cells help your body fight infections and other diseases. A high or low count can point to certain health conditions, but it cannot confirm a diagnosis on its own.
What this test measures
A white blood count measures the total number of white blood cells (leukocytes) in your blood. White blood cells are part of your immune system and help fight infections and other diseases.
What your results mean
Reference ranges vary by laboratory and by your age and sex. MedlinePlus does not publish a single normal range for this test — always read your result against the range printed on your own lab report and discuss it with your provider.
Higher-than-normal results
According to MedlinePlus, a high white blood count (leukocytosis) may be caused by infection, inflammatory disease (such as rheumatoid arthritis), allergy, leukemia or Hodgkin disease, tissue damage from burns or surgery, smoking, stress, reaction to medicine, or pregnancy.
Lower-than-normal results
According to MedlinePlus, a low white blood count (leukopenia) may be caused by bone marrow damage (from infection, disease, or treatments like chemotherapy), cancers that affect the bone marrow, autoimmune disorders (such as lupus), or HIV.
Frequently asked questions
What is a white blood count?
A white blood count measures the number of white blood cells in your blood. White blood cells help your body fight infections.
What can cause a high white blood count?
A high white blood count can be caused by infections, inflammatory diseases, allergies, leukemia, tissue damage, smoking, stress, or pregnancy.
What can cause a low white blood count?
A low white blood count can be caused by bone marrow damage, cancers that affect the bone marrow, autoimmune disorders, or HIV.
Can a white blood count diagnose a disease?
No, a white blood count can show if your count is too high or too low, but it cannot confirm a diagnosis. It is usually done with other tests.
What other names are used for this test?
Other names include WBC count, white cell count, white blood cell count, leukocyte count, and WBC.
Related lab tests
Sources
- MedlinePlus: White Blood Count (WBC) — NIH MedlinePlus
Last updated . Information is aggregated from official public sources and is not a substitute for professional medical care.