Urinary Kidney Injury Molecule 1 (U-KIM-1) as a Predictor of Lupus Nephritis

Abstract
Background: Early detection of kidney affection in sys-temic lupus erythrematosus patients and proper monitoring of lupus nephritis activity is very important step in improving lupus nephritis outcome. Urinary kidney injury molecule-1 is considered as a promising biomarker of kidney injury.
Aim of Study: Use of urinary kidney molecule-1 as an early biomarker of lupus nephritis in systemic lupus erythre-matosus patients and detection of correlation between U– KIM-1 and disease activity lupus nephritis.
Methods: Our study included 45 systemic lupus patients and 15 controls. Patients divided into 3 groups ; group A (SLE without lupus nephritis), group B (SLE with inactive lupus nephritis) & group C (SLE with active lupus nephritis). All patients included in this study are subjected to the following investigations: Urinary Kim-1, complete blood picture, serum urea &creatinine, urine analysis, 24 hour urinary proteins, estimated GFR by CKD-EPI Creatinine Equation, complement 3 & 4, serum albumin, Anti-dsDNA antibody & ESR.
Results: Generally U-KIM-1 was significantly higher in our patients with SLE compared with the healthy control group. Also, patients with nephritis had significantly higher level in comparison to those without nephritis. Our study also showed that patients with active nephritis had significantly higher level of U–KIM-1 in comparison to those patients with inactive nephritis. U-KIM-1 had negative moderate significant correlation with eGFR [–0.62 (0.001)], and Complement C3 [–0.51 (0.001)] and had positive moderate significant corre-lation with serum creatinine [0.44 (0.001)], and renal SLEDAI [0.62 (0.001)]. There was also a strong positive significant correlation between U–Kim-1 and 24h-urinary proteins col-lection [0.71 (0.001)]. Although there was negative weak correlation between U–Kim-1.
Conclusion: Urinary kidney injury molecule -1 (KIM–1) is considered a promising biomarker that can be used in early detection and initial diagnosis of renal affection in systemic lupus erythrematosis, monitoring of activity of lupus nephritis. And hence, can also be used in monitoring response to treat-ment.
Recommendation: Wider studies are recommended to detect cut off points of U-Kim-1 in lupus nephritis & active lupus nephritis.