C3 and systemic lupus erythematosus: Urinary IGHG3 was correlated with hemoglobin level (r, −0.183; p = 0.021), ESR (r, 0.204; p = 0.01), anti-dsDNA antibody positivity (r, 0.262; p = 0.001), C3 levels (r, −0.202; p = 0.011), and SLE disease activity index (r, 0.332; p = 0.01).