IntroductionIn the management of juvenile idiopathic arthritis (JIA), there is a lack of diagnostic and prognostic biomarkers. This study assesses the use of serum calprotectin (sCal) as a marker to monitor disease activity, and as a classification and prognosis tool of response to treatment or risk of flares in patients with JIA. MethodsEighty-one patients with JIA from the CAP48 multicentric cohort were included in this study, as well as 11 non-pediatric healthy controls. An enzyme-linked immunosorbent assay (ELISA) method was used to quantify sCal with a commercial kit.ResultsPatients with an active disease compared to healthy controls and to patients with inactive disease showed an 8-fold and a 2-fold increased level of sCal respectively. sCal was found to be correlated with the CRP and even more strongly with the ESR. Evolution of DAS28 scores correlated well with evolution of sCal, as opposed to evolution of CRP. With regard to CRP, sCal could differentiate forms with active oligoarthritis from polyarthritis and systemic forms. However, sCal brought an added value compared to the CRP as a prognosis marker. Indeed, patients with active disease and reaching minimal disease activity (according to JADAS) at 6 months following the test had higher sCal levels, while patients with inactive disease had higher sCal levels if a flare was observed up to 3 to 9 months following the test.ConclusionsThis study confirms the potential uses of serum calprotectin as a biomarker in the diagnosis and follow-up of JIA.