The Full form of ESR is Erythrocyte Sedimentation Rate. ESR is a blood test that detects and monitors inflammation in the body. It measures the rate at which RBCs (red blood cells) in a test tube separate from blood serum over time, becoming sediment in the bottom of the test tube. The sedimentation rate increases with more inflammation. ESR is also commonly called the Sed rate. Doctors call the ESR test a nonspecific test, as it only confirms the presence or absence of inflammatory activity in the body. Doctors typically use clinical findings, other lab tests, and the person’s health history alongside ESR test results to make a diagnosis. Inflammation usually occurs in the human body as a result of some medical conditions, such as infection, cancer, or an autoimmune disease. Doctors also use the ESR test to monitor how conditions, such as rheumatoid arthritis, an autoimmune condition that causes inflammation in the joints; temporal arteritis, a type of blood vessel inflammation, etc are progressing or responding to treatment. People with low ESR values may have sickle cell anemia, a condition that affects the shape of red blood cells leukemia, a blood cell cancer, a high red blood cell count or congestive heart failure.