White Blood Cell Differential: About This Test
What is it?
A white blood cell differential counts the different types of white blood cells in a blood sample. There are
five major kinds of white blood cells. The numbers of each type of white blood cell give important information
about your immune system.
Why is this test done?
The test helps to measure how the body is responding to different types of infections. It can also help
measure certain allergic reactions. It can sometimes be helpful in finding the stage of leukemia or how the
body is responding to chemotherapy.
How do you prepare for the test?
In general, there's nothing you have to do before this test, unless your doctor tells you to.
How is the test done?
A health professional uses a needle to take a blood sample, usually from the arm.
Your doctor may order a blood smear test to be done at the same time. In this test, a drop of blood is
smeared on a slide and stained with a special dye. The slide is looked at under a microscope. The number,
size, and shape of red blood cells, white blood cells, and platelets are recorded. Blood cells with different
shapes or sizes can help diagnose many blood diseases, such as leukemia, malaria, and sickle cell disease.
How long does the test take?
This test will take a few minutes.
What happens after the test?
Follow-up care is a key part of your treatment and safety. Be sure to make and go to all
appointments, and call your doctor if you are having problems. It's also a good idea to keep a list of the
medicines you take. Ask your doctor when you can expect to have your test results.
Current as of: May 13, 2023
Content Version: 14.0
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