Erythrocyte sedimentation rate and its relationship to hematocrit in giant cell arteritis.

We separated 24 patients with biopsy-proved giant cell arteritis into three groups based on erythrocyte sedimentation rates (ESRs) at clinical presentation: low, 1 to 40 mm/h; high, 41 to 80 mm/h; and very high, greater than 80 mm/h. The presence of anemia in the very high ESR group compared with the low ESR group was the only statistically identified difference. A linear regression analysis confirmed a high degree of inverse correlation between ESR and hematocrit in the subject population. There was no difference in ischemic ocular complications among the three groups. These findings emphasize that the diagnosis of giant cell arteritis should be made predominantly on clinical suspicion with less reliance on the ESR as a diagnostic criterion. Furthermore, the degree of ESR elevation does not predict which patients are at increased risk for the development of ocular complications. Finally, the ESR may not reliably indicate active disease in patients with normal hematocrit values.