Serum procalcitonin does not differentiate between infection and disease flare in patients with systemic lupus erythematosus.

Systemic erythematosus lupus (SLE) is a common autoimmune disease. Disease flares may mimic infection with fever, inflammatory syndrome and chills, sometimes resulting in a difficult differential diagnosis. Elevated serum procalcitonin (PCT) levels have been reported to be predictive of bacterial infections, but with conflicting results. The value of serum procalcitonin has not been assessed in large series of SLE. We aimed to describe the distribution of PCT levels in SLE patients with and without flares, to assess the factors associated with increased PCT levels, and to determine the positive and negative predictive values of increased PCT for bacterial infection in SLE patients. Hospitalized SLE patients were included in a retrospective study. Serum PCT had been assayed, or a serum sample had been frozen on admission, before treatment modification. Serum PCT, measured by an automated immunofluorometric assay, and SLEDAI were assessed at the same time. Some 53 women (median age: 33.7 years, range 16-76) and seven men (median age: 52.5 years ± 19) were included. The median SLEDAI for patients with flare (n = 16, 28%) was 2 (range: 0-29). Five patients (8%) had systemic infection. Only one patient had increased PCT levels. Men had significantly higher PCT levels than women (0.196 ± 0.23 versus 0.066 ± 0.03, p < 0.01) and a significant correlation was observed between PCT, age, erythrocyte sedimentation rate, and C-reactive protein. We conclude that PCT levels were within the normal range in infected and non-infected SLE patients and there was no ability to differentiate SLE patients with or without bacterial infection.

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 microg/l) compared with women (0.066 +/- 0.027 microg/l) (P = 0.009), and in PMR (0.092 +/- 0.027 microg/l) compared with GCA (0.068 +/- 0.026 microg/l) (P = 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.