Erythrocyte Sedimentation Rate (ESR)

A blood test that measures how quickly red blood cells settle at the bottom of a test tube over one hour. When inflammation is present, certain proteins cause red blood cells to clump together and fall faster. This test provides a non-specific marker of inflammation in the body, it cannot pinpoint the exact cause, but an elevated ESR indicates that some type of inflammatory process is occurring. It is often used to help diagnose conditions such as autoimmune disorders (e.g., lupus, rheumatoid arthritis), infections, and certain cancers, as well as to monitor disease activity and treatment response.