A complete blood count, or CBC, with differential blood test reveals information about the number of white blood cells, platelets and red blood cells, including hemoglobin and hematocrit. The blood test also gives information about the size of red blood cells and their hemoglobin concentration, reports MedlinePlus.
The exact results reported with a CBC with differential vary among laboratories. Sometimes the blood test identifies and counts the five types of white blood cells in the blood, including neutrophils, lymphocytes, basophils, eosinophils and monocytes, explains Lab Tests Online. White blood cells fight infections and defend against cancer.
As part of the red blood cell count, a CBC with differential may include a reticulocyte count, which indicates the percentage of young red blood cells present in the blood, explains Lab Tests Online. A CBC with differential may also include other characteristics of oxygen-carrying red blood cells, including the average amount of hemoglobin inside red blood cells and the variation in the size of the red blood cells. A CBC with differential also typically includes the average size of platelets, which are important for blood clotting. Doctors may order a CBC with differential to screen for, diagnose, monitor or evaluate the treatment of a disease or condition.