Normal Sedimentation Rates and Giant Cell Arteritis

To the Editor.—— In their article published in the February issue of theARCHIVES, 1 Neish and Sergent draw attention to possible intracranial small-vessel disease complicating giant cell arteritis (GCA) with a normal erythrocyte sedimentation rate (ESR). The authors argue that the ESR, as a diagnostic test for GCA, should be used as an adjunct to the clinical situation rather than as a diagnostic criterion per se. While this latter view is most laudable, the authors fail to offer their readers any guidance as to how to interpret the ESR that is inappropriately low for a given clinical situation. There are several explanations for a "normal," or relatively low ESR in the context of an active arteritis: (1) prior steroid treatment, which patients often neglect to recall, particularly if it was administered intraarticularly; (2) the variation in ESR inherent to GCA, from day to day or even hour to hour——this