A METHOD FOR CORRECTING THE ERYTHROCYTE SEDIMENTATION RATE FOR VARIATIONS IN THE CELL VOLUME PERCENTAGE OF BLOOD 1

Abstract

The following conclusions are based on 47 individual blood specimens from cases of 17 different diseases. The cell volume percentage of a specimen of blood has an important effect on the rate of sedimentation of the red blood cells. The higher the cell volume percentage, the slower the sedimentation rate; and the lower the cell volume percentage, the faster the rate. The value of the sedimentation test as an index of the severity of infection or tissue damage in the body is greatly increased if a correction is made for the effect of variations in cell volume percentage. A chart has been constructed by means of which the rate of sedimentation of any specimen of heparinized blood with a hematocrit reading between 20 and 55 vols. % of cells may be transposed to the rate which would have obtained had the specimen contained 45 vols. % of cells. The "corrected sedimentation index" obtained by the use of this chart is a reliable index of the severity of infection or tissue damage in the body. The normal limits of the "corrected sedimentation index" are from 0.08 to 0.35 mm. per min.