Erythrocyte sedimentation rate
ESR is directly proportional to the mass of erythrocytes, the difference in the density of erythrocytes and plasma and inversely proportional to the viscosity of the plasma. Reference values of ESR are given in Table.[Titz N., 1997].
Table Reference values of ESR
Table Reference values of ESR
Formation of "coins" and agglutination of erythrocytes, increasing the mass of settling particles, accelerate settling. The main factor affecting the formation of "coins" of red blood cells is the protein composition of the blood plasma. All protein molecules reduce the zeta potential of erythrocytes( a negative charge that promotes mutual repulsion of red blood cells and keeping them in a suspended state), but asymmetric molecules - fibrinogen, Ig, and also haptoglobin - have the greatest effect. Therefore, a particularly pronounced increase in ESR( 60-80 mm / hr) is characteristic of paraproteinemic hemoblast-calls( myeloma, Waldenström's disease).The sensitivity of ESR to the detection of protein pathology of the plasma is higher in the absence of anemia. Other factors influence the zeta potential of erythrocytes: pH of the plasma( acidosis decreases ESR, alkalosis increases), ion charge of plasma, lipids, blood viscosity, presence of anti-erythrocyte antibodies. The number, shape and size of red blood cells also affect sedimentation. Erythropenia accelerates sedimentation, but with severe crescent, spherocytosis, anisocytosis,
, ESR may be low, since the altered form of cells prevents the formation of "coin pillars".
In recent years, the international method for determining ESR - the Westergren method - has been actively used. In this method, capillaries of 200 mm length are used, which increases the sensitivity of the method.
Along with leukocytosis and corresponding changes in the leukocyte formula, an increase in ESR is a reliable sign of the presence of infectious and inflammatory processes in the body. In the acute period with the progression of the infectious process, an increase in ESR occurs, during the recovery period, ESR decreases, but is somewhat slower in comparison with the rate of decrease in the leukocyte reaction. In autoimmune diseases, the measurement of ESR makes it possible to determine the stage of the disease( exacerbation or remission), to evaluate its activity and the effectiveness of treatment. Normal ESR excludes the presence of an inflammatory process.
Table Diseases and conditions accompanied by changes in ESR
Table Diseases and conditions accompanied by changes in ESR
However, the increase in ESR is not a specific indicator for any particular disease. Nevertheless, often in the pathology of its changes have a diagnostic and prognostic value and can serve as an indicator of the effectiveness of the therapy. The definition of ESR should not be used as a screening method in asymptomatic patients. A number of diseases and pathological conditions causing pathological shifts of ESR are reflected in the table.