What Is an Erythrocyte Sedimentation Rate Test and Why Is It Done?
An erythrocyte sedimentation rate test (also called an ESR or sed rate test) measures the speed at which red blood cells fall to the bottom of an upright glass test tube. This measurement is important because when a person’s blood has abnormal amounts of certain proteins in it, they cause red blood cells to clump together and sink more quickly. The ESR helps doctors detect inflammation or irritation in the body that may be caused by infection, some cancers, and certain autoimmune diseases such as rheumatoid arthritis, lupus, and Kawasaki disease. The ESR test alone can’t be used to diagnose any specific disease, however.
