Mechanism and causes of an elevated erythrocyte sedimentation rate
THE CONTEXT
The erythrocyte sedimentation rate (ESR) increases when red cells aggregate and sediment more rapidly. This passage explains how inflammatory proteins promote aggregation and lists conditions associated with elevated ESR.
Protein-mediated red cell aggregation
•
Normally, the negative charge of the red cell membrane prevents aggregation.
•
During inflammation, positively charged immunoglobulins and acute-phase proteins bind to red cell membranes and neutralize their negative charge. The listed proteins include prothrombin, plasminogen, fibrinogen, and C-reactive protein.
•
Neutralization of the membrane charge causes red cells to clump into stacks called rouleaux.
•
These large aggregates sediment more rapidly than individual red cells, increasing the ESR.
Conditions associated with elevated ESR
•
ESR can be elevated in infections, chronic inflammation, pregnancy, malignancy, end-stage renal disease, and nephrotic syndrome.