Erythrocyte sedimentation rate (ESR) is a non-specific test

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Erythrocyte Sedimentation Rate
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• Erythrocyte sedimentation rate (ESR) is a
  non-specific test for inflammation.
• It is easy to perform, widely available,
• Inexpensive making it a widely used screening
  test.
• It is also used a monitoring tool for response to
  treatment in conditions in which it is raised
  (tuberculosis, autoimmune diseases etc).
• Basics
• The ESR test in performed in the laboratory by
  placing anticoagulated blood in an upright tube
  (Westegren's most often).
• At the end of one hour, the rate of the RBC
  sedimentation is measured .

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Factors affecting the ESR

• A- Effect of plasma protein
• Increased in the concentration of fibrinogen
  and Immunoglobulins due to tissue injury will
  increase rouleaux formtion and hence the rate of
  sedimentation. plasma albumin retards
  sedimentation of RBCs.
• B- The RBC size and number
• The size and number of RBCs that show alterations
  in their bioconcavity, like spherocyte and sickle
  cells, usually do not exhibit increase rate,
  unless there is severe anemia.
• Increase red cell mass will retard the
  sedimentation rate e.g. polycythemia.

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• C- Technical factors
• Perpendicularity of sedimentation tube, slight
  deviations from the absolute. Vertical can
  increase the result.
• Temperature (RT 18-25 C) higher temperature cause
  false high results due to reduction in plasma
  viscosity
• Vibration cans reduce the ESR.

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Sedimentation Phases

• The initial lag phase .(10m)
• The phase of rapid RBC falling(40m)
• The packing phase (10m).

• Normal value ESR values tend to rise with age
  and are generally higher in women. ESR is also
  elevated in the black population and those with
  anemia.

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Reference Range

• Adult females 0-20 mm/h
• Adult males 0-15 mm/hr
• Children(lt10) 0-10 mm/hr

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Mechanism

• ESR is determined by the interaction between
  factors that promote (fibrinogen) and resist
  (negative charge of RBCs - that repel each other)
  sedimentation.
• Normal RBCs settle slowly as they do not form
  rouleaux or aggragate together. Instead, they
  gently repel each other due to the negative
  charge on their surfaces.
• Increased rouleaux formation contributes to high
  ESR.
• Rouleaux are stacks of many RBCs that become
  heavier and sediment faster.
• Plasma proteins, especially fibrinogen, adhere to
  the red cell membranes and neutralize the surface
  negative charges, promoting cell adherence and
  rouleaux formation

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Procedure

• Patient must fasting at least 4 hours before
  testing.
• The blood sample must be mixed with anticoagulant
  agent in this test.
• Put 0.4 ml sodium citrate 1.6 ml blood . OR put
  0.2 ml sodium citrate 0.8 ml blood .
• Mix gently with out shaking then put in the
  graded tube and leave it stand vertically on the
  stand for 1 hour.
• Read the amount of plasma that appeared without
  moving it then leave it to the second hour and
  read another time.

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The aggregated RBCs in the rouleaux formation
have a higher ratio of 'mass to surface area' as
compared to single RBCs and hence sink faster in
plasma.
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• ESR of more than 100 mm/hr is strongly associated
  with serious underlying disorders like connective
  tissue disease, infections and malignancies .
• ESR is helpful in diagnosing two specific
  inflammatory diseases, temporal arteritis and
  polymyalgia rheumatica.

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Some conditions with very high ESR gt100 mm/hr

• Multiple myeloma .
• Connective tissue disorders - SLE, RA and other
  autoimmune diseases.
• Tuberculosis.
• Malignancies .
• Severe anemia .

• Drugs such as dextran, methyldopa (Aldomet), oral
  contraceptives,
• penicillamine procainamide, theophylline,
  and vitamin A can increase ESR, while aspirin,
  cortisone, and quinine may decrease it.

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Some conditions with low ESR

• Polycythemia
• Severe Leukocytosis
• Sickle cell disease (anemia(
• Hereditary spherocytosis
• Congestive cardiac failure
• Corticosteroid use
• Hypofibrinogenemia

• Note that sickle cell anemia and spherocytosis
  have low ESR unlike other anemia's.
• This is due to reduced rouleaux formation owing
  to the abnormally shaped RBCs in this condition .

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Important

• Erythrocyte sedimentation rate is a non-specific
  test and is not diagnostic of any particular
  disease. It has a high sensitivity but low
  specificity. Never base a diagnosis solely on an
  ESR value, either normal or high.
• Interpretation of the result should always be
  along with the patient's clinical history,
  examination findings and results of other tests
  done.
• If high ESR is encountered without any obvious
  reasons, patient should be reassured and the test
  repeated after a reasonable amount of time (a
  couple of months).

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• ESR and C-reactive protein (CRP) are both markers
  of inflammation.
• Generally, ESR does not change as rapidly as does
  CRP, either at the start of inflammation or as it
  goes away.
• CRP is not affected by as many other factors as
  is ESR, making it a better marker of
  inflammation.
• However, because ESR is an easily performed test,
  many doctors still use ESR as an initial test
  when they think a patient has inflammation.

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