HMGB1 and juvenile idiopathic arthritis: In patients with JIA, regardless of the disease type, there was statistically significant and positive correlation between serum levels of HMGB1 and ESR (r = 0,574, P < 0.001), CRP (r = 0,600; P < 0.001) and α2-globulin (r = 0,533; P < 0.001) (Figure 3) while weak statistically significant and negative correlation was found between HMGB1 and Hb (r = - 0.362; P < 0.002), Hct (r = - 0.322; P = 0.008) and RBC (r = - 0.285; P = 0.029).