C-Reactive Protein in Idiopathic Inflammatory Myopathies

Abstract

Objectives: To characterize C-reactive protein [CRP] in polymyositis [PM], dermatomyositis [DM], Jo-1 syndrome [Jo-1] and sporadic inclusion body myositis [sIBM].

Methods: C-reactive protein obtained before the start of immunosuppressive therapy was analyzed retrospectively in 61 therapy naïve patients [PM n = 27, DM n = 15, Jo-1 n = 5, sIBM n = 14]. All patients had a diagnosis of idiopathic inflammatory myopathy confirmed by muscle biopsy.

Results: C-reactive protein was significantly higher in DM and Jo-1 compared to PM and sIBM [ANOVA p < 0.001]. The CRP levels less than twice the upper limit were found in 79% of sIBM patients, 85% of PM patients, 20% Jo-1 of patients, 53% of DM patients. C-reactive protein showed no correlation with creatine kinase and erythrocyte sedimentation rate.

Conclusions: The CRP is elevated in a minority of patients with myositis, mostly associated with interstitial lung disease and malignancies.

• C-reacitve protein
• dermatomyositis
• erythrocyte sedimentation rate
• idiopathic inflammatory myopathy
• Jo-1 syndrome
• polymyositis
• sporadic inclusion myositis

Acknowledgements

We thank Prof. Weis [Institute of Neuropathology, Aachen, Germany] for the electron microscopy examination and Dr Kathryn Birch for proof reading the manuscript.

Declaration of interest

The authors report no conflicts of interest.