ESR can be normal in giant cell arteritis and polymyalgia rheumatica

It is potentially dangerous to suggest that normal inflammatory markers can be used to rule out illnesses such as giant cell arteritis and polymyalgia rheumatica.1 Although patients with polymyalgia rheumatica will probably come to no serious long term harm from undiagnosed illness, this cannot be said about giant cell arteritis, where a delayed or missed diagnosis has potentially serious implications, including permanent loss of vision. In these two diseases up to 22.5% of patients can have a normal erythrocyte sedimentation rate (ESR).2 Patients with a delayed diagnosis of giant cell arteritis are often those who present with atypical features,3 and a case review of 80 patients showed that three patients with giant cell arteritis associated blindness had a normal ESR.2 Although normal inflammatory markers make the diagnosis more unlikely, if there is a clinical suspicion, early referral should be sought, especially in suspected giant cell arteritis.4 5