ERYTHROCYTE SEDIMENTATION RATE


I. Measurement/physiology

  1. ESR (Westergren) nl = age/2; add 5 if female
  2. Complex mechanism; approx. rate = 2ac (d1-d2) x g/7.65n
  1. Nl blood: RBCs don't aggregate
  2. Abnl blood:
  1. Rouleaux formation occurs, due to reduction in "zeta potential" (charge on RBC membrane) caused by abundant asymmetrical macro-molecules, e.g. Ig's (Multiple Myeloma) or fibrinogen (tissue necrosis, inf., pregnancy)
  2. RBC agglutination (caused by G's in RBC membrane)
  3. These larger particles fall faster, so higher ESR
  4. Abnl RBC morph. can make rouleaux formation impossible & reduce ESR (e.g. SSA, acanthocytosis, anisocytosis, spherocytosis)

II. Differential dx

  1. ESR usually normal in:
    1. Osteoarthritis
    2. Typhoid fever
    3. Early pregnancy
    4. Angina
    5. Malaria
    6. PUD
    7. SSA (may be?)
    8. Polycyth. Vera
    9. Fever alone
    10. Mono
    11. Atopic conditions
  1. ESR usually high in:
  1. Infection
  2. Inflammation
  3. Neoplasm
  4. Pb poisoning
  5. Thyroiditis
  6. Menstruation (slightly elevated)
  7. Acute MI
  1. Very high ESR (> 100):
  1. 58% are Ca (Multiple Myeloma, lymphoma, metastatic)
  2. 25% inflamm/infectious
  3. 8% renal dis.