Erythrocyte Sedimentation Rate and Its Relationship to Hematocrit Giant Cell Arteritis

To the Editor.  —We read with interest the study by Jacobson and Slamovits¹ investigating the relationship between erythrocyte sedimentation rate (ESR) and hematocrit in giant cell arteritis (GCA). They found a high incidence (63% ) of anemia in their patients with biopsy-proved GCA, as we² and others have reported. Because the Westergren ESR method shows a falsely elevated level in the presence of anemia and could only be corrected by using the corrected Wintrobe method or the determination of zeta sedimentation ratio (ZSR), Jacobson and Slamovits comment that an evaluation of these two methods with the Westergren technique in GCA would be required. We have previously presented such a study.³ Since it has not been published elsewhere, we will briefly summarize our findings.The ZSR is preferred by many clinical laboratories because of its greater speed of determination (three minutes for ZSR vs one hour for older methods),