You have received your test report and are looking for the WBC line. There is a number next to it, but no reference range. Let's go over which numbers are considered normal and what an abnormal result means.
What white blood cells are and why they are counted
White blood cells are blood cells that are part of the immune system. They are produced in the bone marrow and live from several hours to several years. Their main job is to protect against pathogens and remove the products of tissue breakdown.
There are five types. Neutrophils mostly act against bacteria, lymphocytes against viruses. A complete blood count measures the total number of cells, while the leukocyte differential counts the proportion of each type.
- neutrophils;
- lymphocytes;
- monocytes;
- eosinophils;
- basophils.
In case of injury or illness, cells travel to the site. The body releases more of them, and their number in the blood rises. Pus during inflammation is a buildup of dead white blood cells.
The test takes about 10 minutes. Blood is drawn from a vein at the bend of the elbow.
Normal white blood cell count in adults
In adults, the normal range is 4 × 10⁹/L to 11 × 10⁹/L. This is roughly 1% of total blood volume.
If you have questions about your result, contact the doctor who ordered the test. They will explain what the number means and whether further tests are needed.
Normal white blood cell count in children
Children are tested as part of routine screening or when symptoms are present. In newborns, blood is drawn from the heel; in older children, from a finger or vein. Compare the values with the information provided by the doctor.
Why white blood cells can be elevated, for example 12
12 × 10⁹/L is above the upper limit of 11. This is leukocytosis. There are many causes.
Most often it is an infection. It can also be inflammatory diseases such as rheumatoid arthritis, allergies, or tissue damage after a burn or surgery. It occurs with smoking, stress, a reaction to a medication, and during pregnancy.
Less commonly, it is leukemia or Hodgkin lymphoma. A single number does not establish a diagnosis. The doctor looks at the leukocyte differential, symptoms, and other tests.
Why white blood cells decrease
A low count is called leukopenia. The cause is often in the bone marrow: it can be damaged by infection, disease, or chemotherapy. Tumors that affect the bone marrow also lower the cell count.
Other causes include autoimmune diseases such as lupus, HIV, lymphoma, and liver or spleen disease. Some medications produce this effect.
If the cell count falls during treatment, the doctor may change the therapy.
When an abnormal white blood cell count requires a doctor's consultation
The doctor may order a complete blood count with differential, a blood smear, or a bone marrow test.
Reasons to see a doctor include fever, chills, body aches, headache, or a prolonged cough. Or a wound with pus that does not heal. If treatment is already underway, the numbers are used to see whether it is working.
Results are usually ready within a few days, sometimes up to a couple of weeks. If there is no response, call the laboratory or the reception desk. Discuss an unclear report with your doctor.
A change in white blood cells alone is not a reason to call an ambulance. 103 or 112 are needed if the condition is life-threatening: for example, in a serious accident, stroke, or heart attack.
This article is for reference. It does not replace a doctor's consultation: your report should be interpreted by someone who sees you as a whole person.
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This content is for reference and does not replace a doctor's consultation. Medical disclaimer