Procalcitonin at the onset of giant cell arteritis and polymyalgia rheumatica: the GRACG prospective study

Objectives. An epidemic pattern has been reported for GCA and PMR. Immunological studies have shown that an unknown antigen activates the dendritic cells of the adventitia and the type 4 toll-like receptors. Procalcitonin (PCT) is an early marker of bacterial infection. The goal of the study was to assess the level of PCT in GCA and PMR at the onset of the disease. Methods. Patients diagnosed during the 2002–06 period were randomly selected. All the 46 patients fulfilled the ACR or the Hunder criteria, and all blood samples were taken before steroid therapy. Results. PCT was normal in all patients. PCT was slightly increased in men (0.087 � 0.023 � g/l) compared with women (0.066 � 0.027 � g/l) (P ¼ 0.009), and in PMR (0.092 � 0.027� g/l) compared with GCA (0.068 � 0.026 � g/l) (P ¼ 0.018). There was no significant correlation with inflammation markers. Conclusions. These results are not in favour of a bacterial trigger for GCA or PMR. Increased PCT levels in patients with inflammatory syndrome, GCA–PMR symptoms and negative temporal artery biopsy may rule out the diagnosis of GCA and PMR.