Erythrocyte Sedimentation Rate (ESR)

Erythrocyte is another word for red blood cell. The erythrocyte (or, red blood cell) sedimentation rate (ESR) is a test that measures the amount of inflammation in your body. For the test, blood is drawn from a vein in your arm into a special tube. The rate of fall (sedimentation) of red blood cells is then measured, as the red blood cells become sediment at the bottom of the tube, leaving blood plasma at the top of the column. The results are reported in terms of how many millimeters of clear blood plasma are present at the top of the column after one hour. Usually red blood cells fall slowly so that there is little clear plasma left at the top. However, when the blood contains higher amounts of certain proteins involved in inflammation, namely fibrinogen and immunoglobulins (antibodies), the red blood cells fall more rapidly, resulting in an increased ESR. Therefore, sedimentation rate increases with more inflammation. A normal ESR is usually about 0-20 millimeters per hour in females and 0-12 millimeters per hour in males. The ESR is nonspecific, meaning that it does not tell your doctor exactly where the inflammation is occurring in your body and is thus not a very strong indicator of lupus activity.


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