How is it used?When is it ordered?What does the test result mean?Is there anything else I should know?
Conditions or medications that weaken the immune system, such as
HIV infection, chemotherapy, or radiation therapy cause a decrease in white blood cells. The WBC count detects dangerously low numbers of these cells.
The WBC count is used to determine 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.
A WBC count is normally ordered as part of the
complete blood count (CBC). In some circumstances, a WBC count may be ordered to monitor recovery from illness.
What does the test result mean?NOTE: This test has no single number that identifies an abnormal result.
Your lab report (see a sample report) should include
a range of numbers (reference range) that identifies what is expected for you based on
your age, sex, and the method used in that laboratory. You can find more information
about expected results at Reference Ranges
and What They Mean. Lab Tests Online strongly recommends that you discuss the meaning of your test results with your doctor.
An elevated number of white blood cells is called leukocytosis. This can result from bacterial infections,
inflammation,
leukemia, trauma, intense exercise, 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.
Counts that continue to rise or fall to abnormal levels indicate that the condition is getting worse. Counts that return to normal indicate improvement.
Is there anything else I should know?
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.
Smoking may also cause an increased WBC count.
