The zeta sedimentation ratio.

The zeta sedimentation ratio (ZSR) capillary tube, is subjected to four is a measurement similar to the detercycles of dispersion and compaction. mination of the erythrocyte sedimenAt the conclusion of this process, the tation rate (ESR) but possesses sevaral hematocrit of the blood in the red advantages. It is unaffected by anemia cell-containing portion of the capillary and responds in a linear manner to tube is measured. This hematocrit, a increase in fibrinogen and/or gamma measure of the closeness with which globulin. The normal range is identical red cells will approach each other for males and females. A blood sample, under a standardized stress, is the contained within a vertically oriented ZSR. I N i924, ALF WESTERGREN published a paper entitled “Die Senkungscreaktion”-The Sedimentation Reaction. The technique of performing an erythrocyte sedimentation rate determination (ESR) has remained unchanged ever since. In i970, the International Committee for Standardization in Hematology proposed adoption of the Westergren Technique as the standard method. In 197i, the American National Committee for Clinical Laboratory Standards followed suit. The ESR is, thus, the same test, requiring the same amount of time, and subject to the same uncertainties of interpretation in anemic patients as it was 47 yr ago. The ESR has not persisted unchanged because investigators have ignored it. On the average, more than one paper a year has been written on various improvements in sedimentation rate methodology since it was first described. These improvements have been concentrated in three main areas : (1) reducing the amount of blood and/or the time required to perform the test; (2) correclions for the effect of anemia; (3) making the test respond in a linear fashion to changes in assymetrical macromolecules, such as fibrinogen and gamma globulin. Attempts to reduce the time required for the ESR and to speed up the determination have, in general, followed the approach of shortening the tube and decreasing the bore.2 None of the microtechniques has met with wide acceptance because the tubes become more difficult to read as they get shorter, and as the bore goes below 2.5 mm the sedimentation process becomes unstable and blockage of the tube occurs.3 Another commonly used short cut is the elimination of the dilution step, even though a Westergren