what is erythrocyte sedimentation rate

Erythrocyte sedimentation rate (ESR), also known as sed rate, is a blood test that measures how quickly red blood cells settle to the bottom of a test tube. The test indirectly measures the level of certain proteins in the blood, which correlates with the amount of inflammation in the body. The test is commonly used to detect and monitor inflammatory activity caused by various health conditions, such as infections, autoimmune diseases, and cancer. There are no special steps needed to prepare for the test, and slight pain or a sting may be felt when the needle is inserted.