Erythrocyte sedimentation rate (ESR)
Erythrocyte sedimentation rate (ESR) is a non-specific marker of acute inflammation which is seen in a very wide spectrum of pathologies. In recent years it has been sidelined by the use of C-reactive protein and other acute phase markers but it still has an important role to play in the management of some conditions.
Erythrocyte sedimentation rate is the distance that erythrocytes in a sample of anticoagulated blood have fallen in one hour and is measured in millimeters per hour (mm/hr). It is the measure of the concentration of a number of acute phase reactant proteins, especially fibrinogen, relative to the number of red blood cells. In a healthy state red blood cells are roughly the same density as plasma and hence fall slowly. However, in the presence of inflammation or infection cytokines increase the production of acute phase reactant proteins. The higher the concentration of acute phase proteins, the more adherent red blood cells become to each other, resulting in the formation of "rouleax" (red cells clumping together and looking like stacks of coins); the heavier they are and the faster they fall results in a higher erythrocyte sedimentation rate .
It rises within 24-48 hours of a stimulus and falls back slowly following the resolution of inflammation .
The normal erythrocyte sedimentation rate is calculated as age divided by two in men and in women as age plus 10 divided by two. Erythrocyte sedimentation rate is affected by a number of factors unrelated to the acute phase reaction including age, gender, pregnancy status, anemia, red blood cell dysmorphia, obesity and fibrinogen deficiency .
It is poorly sensitive for detecting infection, inflammation or neoplasia, but is very specific for all of these as a grouping, although is not specific for individual diseases . A list is provided below with states of elevated or normal erythrocyte sedimentation rate .
- inflammation (e.g. temporal arteritis)
- infection (e.g. osteomyelitis)
- neoplasia (e.g. gastric cancer)
- red blood cell disorders (e.g. anemia)
- hypergammalobulinaemia (e.g. multiple myeloma)
- female gender
- renal impairment
- nephrotic syndrome
- healthy state
- early infection or inflammation
- false negative due to low protein state from fibrinogen deficiency (either acquired or hereditary), liver disease, and other conditions
- increased number of red cells
- red blood cell disorder/anemias (e.g. sickle cell disease)
- decreased number of red cells
Generally a lower than normal ESR lacks clinical significance.
- increased number of red cells leads to increasing blood viscosity
- red blood cell disorder/hemoglobinopathies (e.g. sickle cell disease)
- impair the ability of erythrocytes to effectively clump together
Clinically C-reactive protein (CRP) is often preferred to erythrocyte sedimentation rate in that it is elevated for longer and is slower to rise. However, erythrocyte sedimentation rate is superior to CRP for detecting low severity chronic bone and joint infections and for monitoring SLE disease severity .
ESR remains an essential prognostic marker for polymyalgia rheumatica and giant cell arteritis .
History and etymology
The discovery of ESR is credited to two individuals, a Scottish surgeon John Hunter (1728-1793), and, a German physician Hermann Nasse (1807-1892) .
The clinical significance of the erythrocyte sedimentation rate (ESR) as a marker of inflammatory processes was first recognized in 1894 by a Polish physician, Edmund F Biernacki (1866-1911) . Unfortunately for Dr Biernacki, the discovery of the clinical significance of ESR has been misattributed to a large number of other individuals, at least partially due to its first appearance in the non-English literature .
One other individual is important to mention, a Swedish physician, Alf Wilhelm Albertsson Westergren (1891-1968). He is chiefly remembered now for his creation of the Westergren method which remains the gold standard test for measuring the ESR .