C3 and lobular neoplasia: Compared with IgAN patients, LN patients had lower serum C3 levels [1.10 (0.96–1.25) g/L vs. 0.37 (0.29–0.53) g/L, P < 0.05] and lower serum C4 levels [0.24(0.21–0.29) g/L vs. 0.08 (0.02–0.29) g/L, P < 0.05].