MyHealthPEI Education Resource – Complete Blood Count (CBC) Test

Why was a CBC ordered?

A CBC is a blood test that checks the different types of cells in your blood. It looks at:

• White Blood Cells (WBC): help fight infections.
• Red Blood Cells (RBC): carry oxygen through your body.
• Platelets (Plt): help your blood clot when you get a cut.

Sometimes, a result might be a little outside the normal range, but that doesn’t always mean something is wrong. If you’re worried, please follow your usual steps for asking health care questions, as recommended by your health care providers.

When is a CBC used? 

Health care providers use a CBC to: 

• Check your overall health.
• To look for signs of infection.
• Make sure your blood is okay before or after surgery.
• To guide medical treatment if you feel weak, tired, have a fever or bruise easily.

What is most important in a CBC result?

• WBC: These cells help to protect your body from getting sick. Major types of white blood cells are neutrophils, lymphocytes, monocytes, eosinophils, and basophils. A small change in these numbers might be okay depending on your age and health.
• RBC and Hemoglobin (Hgb): Red blood cells carry oxygen from the lungs to the rest of the body. Hemoglobin is reviewed especially in cases of fatigue or anemia.
• Plt: Platelets are particularly important in blood clotting.

What could a CBC result find?

Your doctor or nurse practitioner will look at your results based on your age, health, and other factors like pregnancy or past health history. A CBC value that isn't within the normal range may still be normal for you.

• White Blood Cells: A high WBC count could mean you have an infection, or your body is reacting to stress. Low WBCs could be a response to medications like chemotherapy or due to a short-term or long-term illness.
• Red Blood Cells and Hemoglobin: High or low levels of RBCs could mean you have a blood disorder. One example of this is called anemia and it means you have low red blood cells and hemoglobin. Anemia can be caused by internal bleeding, or blood loss after surgery or having a baby.
• Platelets: If your platelet levels are not normal, it might explain why you bruise easily or have problems with bleeding.

This page is just for information. Always talk to your health care provider if you have questions.