An erythrocyte sedimentation rate (ESR) is a blood test that indirectly measures the level of inflammation in the body. During the test, a sample of blood is taken from a vein in the arm and placed in a tall, thin test tube. The red blood cells in the sample gradually settle to the bottom of the tube, and the distance they fall in one hour is measured in millimeters per hour (mm/h). Inflammation can cause the red blood cells to clump together, making them heavier and causing them to settle to the bottom more quickly.

An ESR test can help detect inflammation caused by a variety of medical conditions, including infections, autoimmune diseases, and certain types of cancer. It is often ordered if a person has symptoms such as unexplained fevers, muscle pain, joint pain, headache, or other vague symptoms that cannot be explained. The test can also be used to monitor the progress of an inflammatory disease and to check whether treatment is working.

It is important to note that an ESR test alone cannot diagnose a specific medical condition causing inflammation. Other tests are usually needed to confirm a diagnosis. The normal range for ESR values can vary slightly among different laboratories, but generally, a higher ESR rate means higher levels of inflammation.

Before an ESR test, there is no special preparation required. However, it is important to tell the healthcare provider about any medications or supplements being taken, as some medications can affect the test results[[5]](https://www....