Background/aim: The aim of the study was to evaluate serum calprotectin (CLP) levels in familial Mediterranean fever (FMF) patients and to investigate the utility of CLP in distinguishing patients with attack from patients without attack.

Material and method: FMF patients, rheumatoid arthritis (RA) patients, and healthy controls were included. Serum calprotectin levels were quantified utilizing the enzyme-linked immunosorbent assay (ELISA) method. Receiver operating characteristic (ROC) curve analysis was used to identify the cut-off value of serum CLP level to differentiate FMF patients with attack from those without. Logistic regression analysis was performed to identify predictors.

Results: Significant differences were observed among the three groups concerning white blood cell (WBC), neutrophil, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and serum CLP levels (p = 0.003, p = 0.004, p < 0.001, p < 0.001, and p = 0.002, respectively). Higher ESR, CRP, and serum CLP levels were observed in FMF patients with attacks than those without (all, p < 0.001). Serum CLP was significantly higher in RA patients than in FMF patients in remission (p < 0.001). ROC analysis identified a threshold CLP concentration in FMF with an attack to be 47.1 pg/mL (83.3% sensitivity, 60.6% specificity, AUC = 0.74, 95% CI = 0.63-0.85, p < 0.001). In univariate logistic regression analysis, CLP (β = 1.045, 95% CI = 1.017-1.073, p = 0.001) was predictive of FMF patients experiencing an attack.

Conclusion: Serum CLP proves to be as productive as ESR in illustrating inflammation and demonstrating the existence of attacks in FMF patients.