Temporal arteritis may be part of an immune-mediated process, although the cyclical nature of outbreaks in a study in Minnesota suggests a possible infectious etiology. Complete blood count may reveal leukocytosis, mild anemia, or thrombocytosis. ESR serves as a useful guide to disease activity. Almost one half of patients with temporal arteritis have abnormal results of liver function tests. Chest radiograph may be a useful screening test for a thoracic aneurysm.
Definitive diagnosis relies on a temporal artery biopsy.
Biopsy does not need to be performed urgently. Since infection tends to be patchy or segmental, multiple biopsies may be required. Perform bilateral biopsies if initial biopsy findings prove negative and clinical suspicion remains high. Steroid therapy may affect results of biopsy, but inflammatory changes usually persist for 2-4 weeks after initiation of treatment. Patients generally do not present via emergency medical services.