Complete Blood Count (CBC): About This Test
What is it?
A complete blood count (CBC) is a blood test that gives important information about your blood cells, especially red blood cells, white blood cells, and platelets.
Why is this test done?
A CBC may be done as part of a regular physical exam. There are many other reasons that a doctor may want this blood test, including to:
- Find the cause of symptoms such as fatigue, weakness, fever, bruising, or weight loss.
- Find anemia or an infection.
- See how much blood has been lost if there is bleeding.
- Diagnose diseases of the blood, such as leukemia or polycythemia.
How do you prepare for the test?
You do not need to do anything before having this test.
How is the test done?
A health professional uses a needle to take a blood sample, usually from the arm.
What happens after the test?
- You will probably be able to go home right away.
- You can go back to your usual activities right away.
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 or nurse advice line (811 in most provinces and territories) 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.
Where can you learn more?
Go to https://www.healthwise.net/patientEd
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Current as of: May 13, 2023
Author: Healthwise Staff
Clinical Review Board
All Healthwise education is reviewed by a team that includes physicians, nurses, advanced practitioners, registered dieticians, and other healthcare professionals.
