ENG (erythrocyte sedimentation rate)

The norm of Erythrocyte Sedimentation Rate (ESR) depends on the chosen method. When measured by the Westergren method, the sedimentation rate is always higher than when measured by the Panchenkov method. ESR values measured by the Westergren method are more sensitive to react to a pathological process. The Westergren method is more accurate. When blood is tested using this method, ESR values exceeding 100mm/hour are possible. The length of the capillary in the Panchenkov method is such that a result of 100mm/hour is not possible. Sometimes, rules for “recalculating” from one ESR method to another are recommended. However, these rules can be misleading for a specific patient. Often, ESR pathology is only detected by the Westergren method. The Panchenkov method does not show it. Sometimes, at a certain point, both methods show pathological ESR changes, but during the recovery period, only the Westergren method will indicate ongoing inflammation. Therefore, once a method is chosen for measurement, it should be consistently used. In all cases where ESR is measured, C-reactive protein (CRP) can be determined. The clear advantages of quantitative CRP are as follows: 1) CRP increases faster during illness than ESR; 2) ESR can increase even in the absence of inflammation (e.g., pregnancy, anemia, changes in erythrocyte shape); 3) CRP allows differentiation between bacterial and viral infections; 4) CRP returns to normal immediately upon recovery, while ESR may remain elevated for several weeks after clinical and laboratory indicators have normalized; 5) CRP is not influenced by changes in hemoglobin type or erythrocyte size and shape during testing. Monitoring ESR during the course of lymphogranulomatosis remission period has slight advantages over CRP.

Errors in Clinical ESR Interpretations

1. It is assumed that a decrease in hemoglobin indicates an inflammatory process because ESR is elevated. Antibiotics or other anti-inflammatory measures are prescribed. However, the decrease in hemoglobin itself significantly increases ESR. Some authors even recommend applying an anemia correction coefficient when interpreting ESR.
2. It is assumed that the laboratory is mistaken when ESR remains elevated even after clinical signs of the disease have disappeared. However, it has been found that ESR can remain elevated for several weeks after the remission of an inflammatory reaction and is not related to any pathological process.
3. Upon admission to the hospital, if ESR is detected in a patient, treatment with infusions or blood transfusions is initiated, and ESR is tested again on the same day. The reason for fluctuations is that the ESR indicator is more dependent on hemoglobin or hematocrit than other parameters.
4. In the same healthcare facility, there are several laboratories that use different methods to determine ESR.
5. In patients with lung diseases, especially smokers, the hemoglobin level may be elevated, which completely “masks” the increase in ESR due to inflammation or another cause. ESR is always low if the hemoglobin level is high, even in the presence of severe inflammation.

Source | Handbook of Basic Laboratory Tests | Doctor of Medical Sciences Gintaras Zaleskis