Understanding Blood Tests
~ Amy Cleck, CRNP
We test your blood at each visit at Andrews and Patel. Do you know what the results mean?
Complete blood count (CBC)
The most common lab test that you’ll have done during treatment is called a complete blood count, or CBC. Blood is made up of water, proteins, nutrients, and living cells. A CBC tells your health care team about the cells in your blood. It measures 3 basic types of blood cells:
● White blood cells
● Red blood cells
Each of these cells has a special purpose. And each can be harmed by cancer and cancer treatments.
White blood cells (WBCs)
WBCs fight infection. There are many types of white blood cells and each fights infection in a special way. The total WBC range is 4,500 to 10,500. The most important infection-fighting WBC is the neutrophil (new-truh-fil). The number doctors look at is called your absolute neutrophil count (ANC). A healthy person has an ANC between 2,500 and 6,000. The ANC is found by multiplying the WBC count by the percent of neutrophils in the blood. For instance, if the WBC count is 8,000 and 50% of the WBCs are neutrophils, the ANC is 4,000 (8,000 × 0.50 = 4,000). When the ANC drops below 1,000 it is called neutropenia (new-truh-peen-e-uh). Your doctor will watch your ANC closely because the risk of infection is much higher when the ANC is below 500.
Types of WBCs
● Neutrophils are cells that protect the body from bacterial infections. They move toward bacteria and then swallow them up so the bacteria cannot harm the body.
● Lymphocytes are cells that protect the body against viruses, bacteria, and fungi. One type of lymphocyte (B-cell) produces antibodies that attack and destroy the bacteria and viruses. Another type of lymphocyte (T-cell) can directly attack viruses and bacteria and can stimulate the B-cells to produce antibodies.
● Monocytes are cells that consume dead or damaged cells. They are the “clean-up crew”.
● Eosinophils are cells that kill parasites and contribute to allergic reactions.
● Basophils are cells that release histamines during allergic reactions.
Red blood cells (RBCs)
RBCs carry oxygen to and carbon dioxide away from the cells in your body. The CBC measures red blood cells in many ways, but the simplest measure is either
● Hemoglobin (Hgb), the part of each RBC that carries iron (normal range is 11 to 18 gm.dL) OR
● Hematocrit (Hct), the percent of RBCs in the blood (normal range is 35-54%)
When the Hgb and Hct values fall too low, it’s called anemia (uh-nee-me-uh). Symptoms of anemia include shortness of breath, fatigue, and dizziness.
An elevated hemoglobin or hematocrit can indicate a bone marrow disorder called polycythemia, or could be caused by dehydration.
● Platelets help control bleeding. The normal range for platelets is 150,000 to 450,000.
● You may bruise or bleed easily when your platelet levels are low. The risk of bleeding goes up when platelet levels drop below 20,000. When your platelet count is low, your health care team may call it thrombocytopenia (throm-bo-sy-tuh-PEEN-e-uh).
● Having too many platelets is another problem called thrombocytosis. Having too many platelets can cause clotting disorders.
Please ask your medical professional here at Andrews and Patel if you have any questions about your CBC.
For more information, check out the following websites:
Understanding the CBC More information from Lab Tests Online More information from WebMD Click Here to learn more about Amy Cleck, CRNP