White Blood Cell Count

White Blood Cell Count
Also known as: WBC count, Leukocyte count, White countRelated tests: Complete blood count,

The Test

How is it used?
Conditions or medications that weaken the immune system, such as HIV, infection or chemotherapy, cause a decrease in white blood cells. The WBC count detects dangerously low numbers of these cells.

The WBC count is used to suggest the presence of an infection or leukemia. It is also used to help monitor the body’s response to various treatments and to monitor bone marrow function.

When is it ordered?
A WBC count is normally ordered as part of the complete blood count (CBC), which is ordered for a wide variety of reasons. A WBC count also may be ordered to monitor recovery from illness. Counts that continue to rise or fall to abnormal levels indicate that the condition is getting worse. Counts that return to normal indicate improvement.

What does the test result mean?
NOTE: A standard reference range is not available for this test. Because reference values are dependent on many factors, including patient age, gender, sample population, and test method, numeric test results have different meanings in different labs. Your lab report should include the specific reference range for your test. Lab Tests Online strongly recommends that you discuss your test results with your doctor. For more information on reference ranges, please read Reference Ranges and What They Mean.

An elevated number of white blood cells is called leukocytosis. This can result from bacterial infections, inflammation, leukemia, trauma, or stress.

A decreased WBC count is called leukopenia. It can result from many different situations, such as chemotherapy, radiation therapy, or diseases of the immune system.

Is there anything else I should know?

• Eating, physical activity, and stress can cause an increased WBC count.
• Pregnancy in the final month and labor may be associated with increased WBC levels.
• If you have had your spleen removed, you may have a persistent mild to moderate increased WBC count.
• The WBC count tends to be lower in the morning and higher in the late afternoon. WBC counts are age-related.
• On average, normal newborns and infants have higher WBC counts than adults. It is not uncommon for the elderly to fail to develop leukocytosis as a response to infection.
• There are many drugs that cause both increased and decreased WBC counts.

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