Erythrocyte Sedimentation Rate (ESR) Test

Your erythrocyte sedimentation rate can be determined using one of the two methods:

·         Westergren method: This is the most commonly used ESR method. Your blood is drawn into a Westergren-Katz tube until a level of 200 millimeters (mm). The tube is kept vertical and left at room temperature for an hour. This test measures the distance between the upper end of the blood sample and the topmost layer of RBC’s sedimentation.

·         Wintrobe method: This method is similar to the Westergren method, except that a thinner 100 mm long tube is used. A drawback of this method is that it is less sensitive compared to the Westergren method.

Interpretation of results

The ESR results are reported as the distance that RBCs fall in a test tube, in an hour’s time. It is measured in millimeters per hour (mm/hr).

Some laboratories use different measurements and normal value ranges may vary slightly between laboratories.

Deviation from normal levels indicates the following:

·         Lower than normal ESR levels can be seen in conditions like congestive heart failure, polycythemia, sickle cell disease, severe liver disease, and hypofibrinogenemia.

·         Moderately elevated ESR levels may be caused due to conditions like inflammation, anemia, infection, pregnancy, and aging.

·         Very high ESR levels may be caused due to conditions like a severe infection, which is indicated by an increase in globulin levels, polymyalgia rheumatica, or temporal arteritis. Individuals having multiple myeloma or Waldenstrom's macroglobulinemia (cancers that produces a lot of immunoglobulins) typically have extremely high ESRs even when they don't have inflammation.

·         When a condition is being monitored over time, rising ESRs could mean increasing inflammation or that the treatment isn't working whereas normal or declining ESRs could mean that the treatment is working.