May 23, 2007 9:49:46 PM CEST
Hope you feel like some medical jargon. Here's what I found...
Erythrocyte sedimentation rate (ESR) is one of the traditional tests performed on whole blood in hematology laboratories. ESR measures the distance red blood cells sediment, or fall, in a vertical tube over a given period of time. The measurement of sedimentation is calculated as millimeters of sedimentation per hour and takes greater than one hour to complete. The principle behind ESR is that various "acute phase" inflammatory proteins can affect the behavior of red blood cells in a fluid medium (e.g., decrease the negative charge of RBCs). Inflammatory proteins, such as fibrinogen, will typically appear in the blood, or increase in concentration, during inflammatory processes, such as arthritis. The result is decreased negative charge (zeta-potential) of the erythrocytes that tends to keep them apart, and a more rapid fall of the cells in the analysis tube.
The greater the fall of red blood cells in the vertical tube measured at a given period of time, the higher the ESR. A high (i.e., elevated) ESR is indicative of the presence of inflammatory proteins, (i.e., an active inflammatory processes, such as rheumatoid arthritis, chronic infections, collagen disease and neoplastic disease).
So it seems that it's a test for inflammatory problems.