How does normal erythrocyte sedimentation occur?
Under normal conditions, erythrocytes have a negative surface charge. Due to this, cells with the same charge repel each other and remain suspended in the plasma. The physical cause of their gradual sedimentation is that the relative density of erythrocytes is higher than that of the surrounding plasma.
What is the mechanism of ESR elevation?
The acceleration of sedimentation is associated with changes in the physicochemical properties of blood, primarily the plasma protein spectrum and the ratio of plasma to formed elements.
- Decrease in zeta potential — large-molecule proteins (fibrinogen, immunoglobulins, C-reactive protein, ceruloplasmin, $\alpha$- and $\gamma$-globulins, and other acute-phase proteins) adsorb onto erythrocyte membranes. They reduce the negative charge of the cells, decreasing their mutual repulsion.
- Aggregation — decreased repulsion leads to erythrocyte aggregation with the formation of «rouleaux».
- Increase in the effective density of aggregates — aggregates are less stable in a gravitational field and settle faster.
Acceleration is also influenced by cations (hydrogen, potassium, calcium ions, etc.), which neutralize the negative charge of intact erythrocyte membranes, cause a reversal to a positive charge, and promote adhesion of oppositely charged cells. In immunopathological conditions and tumor growth, adhesive transmembrane glycoproteins may become involved in the process.
What conditions and substances increase ESR?
The increase in this parameter is caused by rising concentrations of substances with pro-aggregant effects: fibrinogen, globulins, C-reactive protein, ceruloplasmin, and other acute-phase proteins; it is also associated with dysproteinemia, paraproteinemia, or changes in acid-base balance.
- Inflammatory processes — bacterial infections, infectious and inflammatory diseases, inflammation of various origins, tuberculosis. An increase in ESR is described in acute viral hepatitis as a marker of inflammation, in alcoholic hepatitis, and in ovarian tumor torsion. An increase in ESR is one of the CBC changes in the general reaction to the tuberculin test (Koch's test).
- Rheumatic and autoimmune diseases — accompanied by changes in plasma protein composition.
- Oncological diseases — tumor diseases, especially those accompanied by paraproteinemia; Hodgkin's lymphoma, multiple myeloma, non-Hodgkin lymphomas with paraproteinemia.
- Anemia — a decrease in the erythrocyte count leads to accelerated sedimentation.
- Alkalosis — a shift in pH toward the alkaline side increases ESR.
- Endocrine and metabolic factors — diabetes mellitus, thyrotoxicosis, hypercholesterolemia.
- Physiological states and hormones — stress, pregnancy, and the influence of steroid hormones: glucocorticoids and estrogens.
- Kidney and liver pathologies.
What causes a decrease in ESR?
A decrease in ESR is associated with the following conditions:
- Erythrocytosis — an increase in the erythrocyte count, hemoconcentration.
- Acidosis — a shift in pH toward the acidic side.
Class and exam questions
Why does anemia accelerate ESR?
In anemia, the erythrocyte count decreases, which leads to accelerated sedimentation.
Which proteins accelerate erythrocyte sedimentation?
Large plasma molecules have the greatest impact: fibrinogen and immunoglobulins. Accelerated ESR is also associated with C-reactive protein, ceruloplasmin, other acute-phase proteins, and $\alpha$- and $\gamma$-globulins.
How does the erythrocyte membrane charge affect ESR?
Normally, erythrocytes have a negative surface charge, which ensures their mutual repulsion. Plasma proteins reduce the negative charge of the erythrocyte membrane, decrease repulsion, and promote aggregation into «rouleaux», which settle faster. Cations can also neutralize the negative charge of membranes and promote adhesion of oppositely charged cells.
What else to study on this topic
- Acute-phase proteins of inflammation
- Physicochemical properties of blood
- Anemia and erythrocytosis
- Acid-base balance of blood (acidosis and alkalosis)
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