A complete blood count or CBC is a blood test that measures many different parts and features of your blood, including:
Red blood cells, which carry oxygen from your lungs to the rest of your body
White blood cells, which fight infection. There are five major types of white blood cells. A CBC test measures the total number of white cells in your blood. A test called a CBC with differential also measures the number of each type of these white blood cells
Platelets, which help your blood to clot and stop bleeding
Hemoglobin, a protein in red blood cells that carries oxygen from your lungs and to the rest of your body
Hematocrit, a measurement of how much of your blood is made up of red blood
A complete blood count may also include measurements of chemicals and other substances in your blood. These results can give your health care provider important information about your overall health and risk for certain diseases.
