A complete blood count, also known as a full blood count, is a set of medical laboratory tests that provide information about the cells in a person’s blood. The CBC indicates the counts of white blood cells, red blood cells and platelets, the concentration of hemoglobin, and the hematocrit.

An erythrocyte sedimentation rate (ESR) is a blood test that that can show if you have inflammation in your body. Inflammation is your immune system’s response to injury, infection, and many types of conditions, including immune system disorders, certain cancers, and blood disorders. Erythrocytes are red blood cells.