ESR (Erythrocyte Sedimentation Rate)

Overview

ESR measures the rate at which erythrocytes settle in anticoagulated blood over one hour, serving as a nonspecific indicator of inflammation through increased plasma proteins like fibrinogen and globulins that cause red blood cell rouleaux formation. It reflects the acute phase response but lacks organ specificity. Elevated ESR indicates inflammatory conditions such as infections, autoimmune diseases, and malignancies, while low levels are normal or seen in conditions like polycythemia or hypofibrinogenemia. ESR is clinically useful for screening, monitoring disease activity, and assessing response to treatment in chronic inflammatory states.

Clinical Use Cases

  • Screening for inflammatory conditions like temporal arteritis and polymyalgia rheumatica.
  • Monitoring disease activity in rheumatoid arthritis, systemic lupus erythematosus, and other autoimmune disorders.
  • Evaluating infection, malignancy, or occult disease in nonspecific presentations.
  • Assessing response to anti-inflammatory therapy.

Specimen Types

  • Whole blood (citrate or EDTA anticoagulated).
  • Rarely serum (Westergren method requires whole blood).

Measurement Methods

  • Westergren method (gold standard: 200 mm Westergren tube).
  • Wintrobe method (historical, less common).
  • Automated ESR analyzers using infrared detection or photometric methods.

Test Preparation and Influencing Factors

  • No fasting required.
  • Elevated by anemia, pregnancy, age, female sex, obesity, and hypergammaglobulinemia.
  • Decreased by polycythemia, sickle cell disease, hypofibrinogenemia, and extreme leukocytosis.
  • Improper anticoagulant ratio, delayed testing (>4 hours), or temperature extremes affect results.

Synonyms

  • Sed rate.
  • Sedimentation rate.
  • ESR.

Further Reading

  • ESR (Erythrocyte Sedimentation Rate); MedlinePlus;