What is a Complete blood count (CBC)?
A complete blood count (CBC) is a blood test that is commonly ordered when your doctor thinks you might have a certain condition or as a part of a complete physical exam.
A complete blood count test measures several components of your blood, including:
- Red blood cells, which carry oxygen.
- White blood cells, which fight infection.
- Hemoglobin, a protein that carries oxygen in red blood cells.
- Hematocrit, the ratio of the volume of red blood cells to the total volume of blood.
- Platelets, which help with blood clotting.
The CBC reports how many cells there are in the blood, and their physical characteristics, such as shape, size, and content.
Why would I get a Complete blood count (CBC)?
Your doctor may order a CBC when you have signs of inflammation, infection, bleeding, or bruising. It is also used to monitor medical treatment and evaluate your overall health.
It can help in the diagnosis of many diseases like leukemia, cancer, autoimmune conditions (diseases in which the body's immune system attacks the body), and bone marrow failure.
What happens during a Complete blood count (CBC) test?
You do not have to prepare for a CBC. During the test, a member of your health care team takes a blood sample by inserting a needle into a vein in your arm and collect blood into a vial or syringe.
What to expect after the test is done?
You can return to your usual regular activities immediately after the test. Results usually appear on the same day. Your doctor will analyze these results and tell you if there is something abnormal that requires additional testing.
Results outside the normal range don’t necessarily require a follow-up. This depends on many factors including your age and the reason your doctor recommended this test. Your doctor may need to look at the results of a CBC along with other blood tests to determine if additional tests may be necessary.
If your results are significantly below or above the normal ranges, you may be referred to a hematologist, a doctor who specializes in blood disorders.
Mayo Clinic: Complete blood count (CBC)
Cleveland Clinic: Complete Blood Count