While abnormal in humans, rouleaux formation can be a normal physiological finding in horses, cats, and pigs. Rouleaux formation can also occur in association with some lymphoproliferative disorders in which one or more paraproteins are secreted in high amounts. The red cells form stacks called rouleaux which settle faster, due to their increased density. When an inflammatory process is present, the high proportion of fibrinogen in the blood causes red blood cells to stick to each other. The ESR is governed by the balance between pro-sedimentation factors, mainly fibrinogen, and those factors resisting sedimentation, namely the negative charge of the erythrocytes ( zeta potential). Since the introduction of automated analyzers into the clinical laboratory, the ESR test has been automatically performed.
To perform the test, anticoagulated blood is traditionally placed in an upright tube, known as a Westergren tube, and the distance which the red blood cells fall is measured and reported in millimetres at the end of one hour. It is a common hematology test, and is a non-specific measure of inflammation. The erythrocyte sedimentation rate ( ESR or sed rate) is the rate at which red blood cells in anticoagulated whole blood descend in a standardized tube over a period of one hour. The millimeters of transparent fluid present at the top portion of the vertical tube after an hour. The rate of sedimentation of erythrocytes in a vertical tube over an hour. Sedimentation rate, Westergren ESR, ESR, sed rate The ESR is the height (in mm) of the colourless portion at the top of the pipette after one hour. Westergren pipet array on StaRRsed automated ESR analyzer.
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