Diagnosis of Giant Cell Arteritis Erythrocyte sedimentation rate (ESR), C-reactive protein, and complete blood count (CBC) Biopsy, usually of the temporal artery Sometimes, temporal artery ultrasound Giant cell arteritis is suspected in patients > 55 if any of the following develops, especially if they also have symptoms and laboratory evidence of systemic inflammation: A new type of headache Any new symptom or sign compatible with ischemia of an artery above the neck Jaw muscle pain during chewing Temporal artery or scalp tenderness Unexplained subacute fever or anemia The diagnosis of giant cell arteritis is more likely if patients also have symptoms of polymyalgia rheumatica.