Erythrocyte Sedimentation Rate

Erythrocyte Sedimentation Rate (ESR):
Common laboratory test. Rate at which red blood cells settle out of blood (expressed as millimetres per hour of RBC’s in a standard tube – Westergren (use 200mm tube and has a dilution step) or Wintrobe method (uses a 100mm tube and has no dilution step) – important measure of inflammatory disease activity. – it is an indirect measure of changes in the acute phase reactants.
Normal values are 0-15mm/hr for males and 0-20mm/hr for females.
Increase  infection, cancer, inflammatory conditions, pregnancy, post operative. All increased if blood to be tested is stored for a prolonged period.
Increase is due to increase in aggregated clumps of RBC’s that settle more rapidly. Normally RBC’s repel each other due to electrical charge on surface, but during inflammatory process  more asymmetrically charges RBC’s  less repulsion.
Decrease  afribrinogenaemia, agammaglobulinaemia. Falsely low readings occur in sickle cell disease, heart failure, polycythemia.

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