Biomarkers Tests

Complete Blood Count

The complete blood count (CBC) is one of the most frequently ordered blood tests. It is essential to know that blood consists of two major parts: plasma and cellular elements. The plasma is the part of the blood that is liquid, which allows the blood to flow smoothly. The other part of the blood consists of blood cells.

The blood cells are white blood cells (WBC)red blood cells (RBC), and platelets. Each of these types of cells carries out specific and vital functions.

The complete blood count test measures the quantity of all the different types of cells in the blood. It also provides some valuable information on other parameters related to each type of blood cell.

How does a complete blood count (CBC) test is made? Blood is collected by inserting a needle into a vein and allowing it to flow into a tube. Later the blood sample gets to the laboratory, and the red blood cells, white blood cells, and platelets get counted. The CBC is used to test for, diagnose, and monitor many different conditions.

The CBC test gets a lot of information from your blood sample:

  • White blood cells (WBCs) their number and their types. Your body has five kinds of white blood cells. All play a role in fighting infections. High numbers of WBCs, or a specific type of WBC, may mean you have an infection or inflammation somewhere in your body. Low numbers of WBCs may mean you are at risk for infections.
  • Numbers of the red blood cells (RBCs). RBCs carry oxygen throughout the body and remove excess carbon dioxide. Too few RBCs may be a sign of anemia or other diseases. In rare cases, too many may cause problems with blood flow.
  • The size of your red blood cells varies. This test is known as the red cell distribution width (RDW). For instance, you may have more significant differences in red blood cell size if you have anemia.
  • Hematocrit. The portion of red blood cells in a certain amount of whole blood. A low hematocrit may be a sign of too much bleeding. Or it might mean that you have iron deficiency or other disorders. A higher than average hematocrit occurs when one is dehydrated or by some other conditions.
  • Hemoglobin. Hemoglobin is a protein in red blood cells. It carries oxygen from your lungs to the rest of the body. Abnormalities can be a sign of problems ranging from anemia to lung disease.
  • Red blood cells average size. This test is known as the mean corpuscular volume (MCV). MCV goes up when your red blood cells are bigger than expected. It happens if you have anemia caused by low vitamin B12 or folate levels. If your red blood cells are smaller, this can mean other types of anemia, such as iron deficiency anemia.
  • A platelet count. Platelets are cell fragments that play a role in blood clotting. Too few platelets may mean you have a higher risk of bleeding. Too many may tell several possible conditions.
  • Mean corpuscular hemoglobin. This test measures how much hemoglobin your red blood cells have.


Test results may vary depending on your age, gender, health history, the method used for the test, and other things. Your test results may not mean you have a problem. Ask your healthcare provider what your test results mean for you. 

The information on is NOT intended to replace a one-on-one relationship with a qualified health care professional and is not intended as medical advice.

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