C3 and systemic lupus erythematosus: Results: In the group comparison, a significant difference was observed in the following parameters: albumin, complement C3, antinuclear antibody (ANA), anti-double-stranded DNA antibody (anti-ds-DNA Ab), proteinuria g/24h (proteins from 24 hours collected urine), and Systemic Lupus Erythematosus Activity Index/renal (SLEDAI/r) (p < 0.000).