Urinary ferritin creatinine ratio, a potential biomarker for lupus nephritis activity.

Abstract

Ferritin has gained increasing attention in systemic lupus erythematosus (SLE).This study aimed to investigate the clinical significance of urinary ferritin/creatinine ratio in lupus nephritis (LN). Samples from 62 SLE patients (35 with LN and 27 without LN) and 62 healthy controls were evaluated. There were nine patients who underwent renal biopsy. The amount of urinary ferritin was measured by enzyme-linked immunosorbent assay (ELISA) and normalized by the amount of urinary creatinine to obtain the urinary ferritin/creatinine ratio (UFCR). The relationships between UFCR and inflammatory markers, laboratory indicators, as well as the activity index (AI), and chronicity index (CI) of KBs were also investigated by correlation analysis. UFCR level in severe active SLE patients was significantly higher than that in inactive SLE patients (P < 0.01) or healthy controls (P < 0.01). In addition, UFCR level was significantly increased in the patients with LN when compared with those without LN (P < 0.01).Correlation analysis showed that UFCR level is positively correlated with Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) (P < 0.01), 24h urine protein quantitation, serum creatinine, serum cystatin C, and GFR. The UFCR levels was significantly positively correlated with AI (P < 0.05) but not CI (P = 0.614) of KBs. UFCR level is a potential biomarker for the kidney injury in LN. Key Points • UFCR level is significantly increased in LN patients. • UFCR level is positively correlated with SLEDAI. • UFCR level is closely related to kidney injury indicators. • UFCR level is a potential biomarker for the kidney injury in LN.