Evaluation of Serum C4d Levels in Patients with Systemic Lupus Erythematosus and its Relation to Lupus Nephritis

Aim: Lupus nephritis (LN) is an inflammatory reaction that develops in patients with systemic lupus erythematosus (SLE). In Iran, a significant proportion of patients diagnosed with SLE develop lupus nephritis. Kidney biopsy is the gold standard for diagnosis of LN. Some studies have suggested that activation of the complement system, leading to the production of C4d, might play a role in the pathogenesis of LN. The purpose of this study was to evaluate the value of C4d as a less invasive method for early diagnosis of lupus nephritis 
 
Materials & Methods: This study was conducted in Ghaem Medical Centre, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran in 2018-2019.
In total, 43 cases, 29 females and 14 males, were selected. This included 11 healthy controls, 9 cases diagnosed with SLE without LN, 13 cases with LN and 10 cases with chronic kidney disease (CKD). Data analysis was performed using Statistical Package for the Social Sciences (SPSS), Version 23.0.
 
Results: Statistical analysis shows that there is a significant difference between the groups in terms of age (P = 0.001). This difference was significant between normal and CKD (P = 0.002), lupus and CKD (P = 0.004), lupus nephritis and CKD (P = 0.001). Creatinine levels were significantly different in head to head comparisons between all groups (p<0.05) except healthy controls and SLE patients without LN (p=0.06). Estimated GFR was not significantly different when comparing healthy controls with SLE patients with LN (p=0.06) and without LN (p=0.41), but it was significantly different when comparing other groups. Serum levels of C4d was not significantly different in head to head comparisons between the 4 studied groups (P>0.05).
 
Conclusion: This study showed that there is not a significant correlation between lupus nephritis and serum C4d levels in patients diagnosed with SLE.
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