C3 and systemic lupus erythematosus: SLEDAI: Systemic Lupus Erythematosus Disease Activity Index; Cr: creatinine; C3: complement component 3; C4: complement component 4; ESR: erythrocyte sedimentation rate; CRP: C-reactive protein; 24 hr urine protein: 24-hour urine protein; TC: total cholesterol; LDL: low-density lipoprotein; HDL: high-density lipoprotein; TG: triglycerides; VLDL: very low-density lipoprotein