Erythrocyte Sedimentation Rate (ESR)
The Erythrocyte Sedimentation Rate (ESR) test is a simple blood test that helps detect inflammation in the body. It measures how quickly red blood cells settle in a tube over one hour, expressed in millimeters per hour(mm/hr). Erythrocytes are red blood cells that carry oxygen throughout the body. When blood is placed in a tall, thin test tube, red cells gradually settle to the bottom. The sedimentation rate reflects how fast this happens. Inflammation causes proteins (like fibrinogen) to make red cells clump together, so they sink faster. Thus, ESR is a nonspecific marker of inflammation.
Test is used to detect inflammation due to infection, autoimmune disease, or cancer, monitor chronic inflammatory conditions such as rheumatoid arthritis, lupus or temporal arteritis. It also essential to assess response on treatment in inflammatory diseases. Further the test can be used to investigate symptoms like prolonged fever, weight loss, or joint pain.
During the test, a blood sample is drawn from the vein. The sample is placed in a vertical tube (Westergren or Wintrobe method). The distance red blood cells fall in one hour is measured in millimeters per hour (mm/h). There are no special preparation (like fasting) required.
Reference ranges vary slightly by lab, but typical values are:
| Group | Normal ESR (mm/h) |
|---|---|
| Men (under 50 years) | 0 – 15 mm/h |
| Women (under 50 years) | 0 – 20 mm/h |
| Men (over 50 years) | 0 – 20 mm/h |
| Women (over 50 years) | 0 – 30 mm/h |
| Children | 0 – 10 mm/h |
| Newborns | 0 – 2 mm/h |
High ESR values can indicate the presence of Infections (e.g., tuberculosis), autoimmune diseases (e.g., rheumatoid arthritis, lupus), cancers (especially blood cancers), chronic kidney disease or pregnancy (mildly elevated is normal). Low ESR values may be caused by polycythemia (too many red blood cells), sickle cell anemia and abnormal red cell shapes (affect settling). ESR is nonspecific therefore a high result does not pinpoint the exact cause and can only signal that inflammation may be present. No fasting is needed; eat and drink normally. Medications such as some (like steroids or NSAIDs) can affect ESR results. Repeat testing may be required to monitor trends over time. ESR is often combined with other tests (like C-reactive protein, CRP) for a clearer picture.
The ESR test is a simple, inexpensive blood test that helps detect and monitor inflammation. ESR is not a diagnostic test on its own, results must be interpreted alongside other tests and your clinical history.
