Patient education: Complete blood count (CBC) (The Basics)
Written by the doctors and editors at UpToDate
What is a complete blood count?
— A complete blood count (also called a “CBC”) is a test that gives information about the 3 main types of cells in the blood. The cells include:
●Red blood cells – These cells carry oxygen to your body.
●White blood cells – These cells fight infections. There are 5 main types of white blood cells. Each type works in a different way.
●Platelets – Platelets are actually pieces of cells, not whole cells. They help clots form so that you stop bleeding after you are injured.
A CBC measures the number of each of the 3 types of cells in your blood and shows if your levels are low, normal, or high.
The test usually also measures:
●How much space the red blood cells take up in your blood, called the “hematocrit”
●How much “hemoglobin” is in your blood – Hemoglobin is the protein that carries oxygen in your blood.
●Information about the size and shape of your red blood cells
Some CBC blood tests also include a “white blood cell differential.” This tells you how many of each of the different types of white blood cells you have. It also shows if you have any abnormal white blood cells.
Why might a doctor order a CBC?
— A CBC is done for many reasons. Your doctor might order this test when you have a regular check-up. This might be done to check for anemia, or if you have an infection or signs of bleeding. If you have certain other diseases or take certain medicines, you doctor or nurse might check your CBC regularly to make sure your blood counts are okay.
What can a CBC show? — The results of the test can show if you have different health conditions. Examples include:
●Anemia – This is the medical term for too few red blood cells.
●Polycythemia – This is the medical term for too many red blood cells.
●An infection, which causes your white blood cell level to rise
●Bleeding or clotting disorders – If your blood makes too many or too few platelets, you might have a bleeding or clotting disorder.
●Problems with the body’s infection-fighting system if your white blood cell level is low
●Conditions or medicines that affect your bone marrow – The bone marrow is the space inside some of your bones that makes all 3 types of blood cells.
This topic retrieved from UpToDate on: Mar 09, 2017.