Clinical significance of urine hepcidin in lupus nephritis

Objective To test the level of urine hepcidin (Hepc) in systemic lupus erythematosus (SLE) patients with renal damage, study the relationship between the level of urine Hepc and lupus nephritis (LN), and to further investigate the relationship between urine Hepc and active LN. Methods This experiment included 38 healthy subjects (29 females and 9 males) and 54 cases of SLE (46 females and 8 males). According to the renal damage, all SLE patients were divided into SLE non-LN group (12 cases) and SEL LN group (42 cases). The enzyme-linked immunosorbent assay (ELISA) was used to measure the level of urine Hepc. Forty-two cases of LN were divided into inactive LN group (10 cases) and active LN group (32 cases) according to Renal-Systemic Lupus Erythematosus Disease Activity Index (R-SLEDAI). The level of urine Hepc was compared between inactive LN group and active LN group, and the relationship between the R-SLEDAI and urinary Hepc was analyzed. At the same time, the activity of LN was predicted according to the Hepc values, and the sensitivity and specificity were analyzed by receiver operating characteristic curve (ROC curve). Results The level of urine Hepc in SLE LN group was significantly higher than SLE non-LN group and healthy control group (both P<0.01). The level of urine Hepc in active LN group was significantly higher than that in inactive LN group (P<0.001). The urine Hepc in LN patients was positively correlated with the R-SLEDAI score (r=0.313, P=0.043), and there was no correlation between SLEDAI and renal RSLEDAI score (P>0.05). Cut-off in urine Hepc was 7.483 ng/ml (90.62% for sensitivity, and 80% for specificity). The area under the ROC curve was 0.897, greater than that of complement C3, C4, serum creatinine and serum anti ds-DNA antibody, but less than that of 24-h urinary protein quantity. Conclusions The expression level of urine Hepc in the SLE patients with renal involvement may be a new indicator of LN activity.