An ESR test measures the erythrocyte sedimentation rate to detect inflammatory activity in the body, according to Mayo Clinic. The test is used in conjunction with other tests to help diagnose and monitor the progression of inflammatory diseases.
The test gauges the distance red blood cells fall in one hour within a test tube. Since inflammation causes cells to clump together, these denser cells fall to the bottom faster. The normal range is 0 to 22 mm/hr in men and 0 to 29 mm/hr in women. Conditions such as anemia, high cholesterol, kidney problems and pregnancy may affect the results of an ESR test, according to Mayo Clinic.