Comparison of laboratory features of pediatric multisystem inflammatory syndrome with other invasive febrile diseases

Abstract Introduction: COVID-19 does not seem to affect children as much as adults. However, a new emerging entity associated with COVID-19, called multisystem inflammatory syndrome in children (MIS-C), has been reported. The aim of this study was to compare the laboratory characteristics of children with MIS-C and other invasive febrile diseases. Methods: A single-center prospective study was conducted in a Pediatric Intensive Care Unit of a university hospital. The same laboratory panel was performed in both groups: C-reactive protein, procalcitonin, erythrocyte sedimentation rate, interleukin-6, N-terminal pro-B-type natriuretic peptide, troponin T, ferritin, activated partial thromboplastin time, prothrombin time, fibrinogen, and lymphocyte count. Results: Forty-one patients were included, twenty-four in the MIS-C group and seventeen in the non-MIS-C group. MIS-C predominantly affected older children and adolescents (median age 12 years). Lymphopenia was identified in every patient in the MIS-C group. NT-proBNP, troponin T, CRP, ESR, and fibrinogen levels were significantly higher in the MIS-C group. IL-6 levels were similar between the two groups (p=0.745). Conclusions: Patients with MIS-C had a laboratory profile characterized by elevated cardiac and inflammatory markers, with lymphopenia being a common feature. IL-6 levels should be interpreted with caution for therapeutic decisions in patients with MIS-C, as they are similar to those seen in patients with other febrile diseases.