Logistic regression analysis was used to examine whether CysC was associated with proteinuria, hematuria, anemia, neutropenia, lower lymphopenia, complement 3 (C3) levels, anti-dsDNA, and SLEDAI scores, which revealed significant associations between CysC levels and proteinuria, anti-dsDNA, lower C3 levels, and SLEDAI scores in patients with SLE (Fig. 5A–D). This evidence concerns the gene C3 and lymphopenia.