Markedly elevated acute-phase responses, i.e. erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) are the most important immediate diagnostic tests in the diagnosis of A-AION(anterior ischemic optic neuropathy) and its differentiation from NA-AION. Although high ESR is traditionally emphasized as a sine qua non(必要條件) for diagnosis of giant cell arteritis(GCA), there are numerous reports of “normal” or “low” ESR in patients with positive temporal artery biopsy for giant cell arteritis. In our series, we had some patients with ESR as low 4~5 mm/hr with positive biopsy. Thus, the rule is normal ESR does not rule out giant cell arteritis. CRP, on the other hand, as a much more reliable test to diagnose giant cell arteritis. A combination of ESR with CRP gave the very best specificity (97%) for detection of giant cell arteritis. We always use both tests in all our patients, for diagnosis of giant cell arteritis and monitoring of steroid therapy.

Other hematological tests which can help in the diagnosis of giant cell arteritis include the presence of thrombocytosis, anemia, elevated white blood cell count and low hemoglobin and hematocrit levels. In conclusion, the combined information provided by ESR, CRP, platelet and white blood cell count and hemoglobin(Hb) and hematocrit levels(Hct) is highly useful in diagnosis of giant cell arteritis, although none of them is individually 100% sensitive and specific.