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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. It is a common hematology test, and is a non-specific measure of inflammation .
A laboratory ultracentrifuge. In chemistry, a Svedberg unit or svedberg (symbol S, sometimes Sv [a]) is a non-SI metric unit for sedimentation coefficients.The Svedberg unit offers a measure of a particle's size indirectly based on its sedimentation rate under acceleration (i.e. how fast a particle of given size and shape settles out of suspension). [1]
The flat surface of the discoid RBCs gives them a large surface area to make contact with and stick to each other; thus forming a rouleau. They occur when the plasma protein concentration is high, and, because of them, the ESR (erythrocyte sedimentation rate) is also increased. This is a nonspecific indicator of the presence of disease.
The sedimentation coefficient has units of time, expressed in svedbergs. One svedberg is 10 −13 s. The sedimentation coefficient normalizes the sedimentation rate of a particle to its applied acceleration. The result no longer depends on acceleration, but only on the properties of the particle and the fluid in which it is suspended.
Erythrocyte aggregation is the main determinant of blood viscosity at low shear rate. Rouleaux formation also determines Erythrocyte sedimentation rate which is a non-specific indicator of the presence of disease. [6] Influence of erythrocyte aggregation on in vivo blood flow is still a controversial issue. [7]
Sedimentation rate may refer to: Sedimentation rate of particles in a liquid, described by Stokes' law; Erythrocyte sedimentation rate, a medical test for inflammation;
Under the heading "Normal Values", in the subsection "Adults", there is a serious contradiction between the formula for ESR and the table beneath it. According to the table, for a 90-year old man, the normal upper limit for ESR value is 19. But according to the formula, the normal upper limit is (90 + 0)/2 = 45.
However, sedimentation rates near the mouths of large rivers with high discharge can be orders of magnitude higher. [1] Biogenous oozes accumulate at a rate of about 1 cm per thousand years, while small clay particles are deposited in the deep ocean at around one millimetre per thousand years. As described above, manganese nodules have an ...