Full blood count as an ancillary test to support the diagnosis of giant cell arteritis.

We conclude that the presence of thrombocytosis and high NLR, PLR, ESR and CRP can all be used clinically to support the diagnosis of GCA prior to biopsy. Of particular note, in multivariate modelling the presence of thrombocytosis is a stronger predictor of a positive temporal artery biopsy than ESR. Therefore, careful consideration of the findings in a full blood count can be used to predict the likelihood of a positive temporal artery biopsy in patients with suspected GCA.