Serum S100A8 levels differed according to fever and central nervous system (CNS) involvement (p < 0.001 and p = 0.049, respectively), and urine and salivary S100A8 showed significant differences in arthritis and malar rash, respectively (p = 0.038 and p = 0.018, respectively). Here, S100A8 is linked to arthritic joint disease.