The Role of urinary kidney injury molecule 1 (KIM-1) in monitoring the treatment response in Egyptian Lupus Nephritis Patients.

Lupus nephritis (LN) affects almost two-thirds of systemic lupus erythematosus (SLE) patients. Despite initial aggressive therapy, up to 25% of patients with LN will progress to permanent renal damage. Conventional serum markers for LN lack the sensitivity of an ideal biomarker. Urinary kidney injury molecule-1 (UKIM-1) is an excellent biomarker for early diagnosis of acute kidney injury and predicting renal outcomes. This study intended to determine the predictive performance of UKIM-1 among LN patients in response to induction therapy by assessing and correlating its levels with renal disease activity. The study included 60 SLE patients divided into 20 SLE patients with active lupus nephritis, 20 SLE patients with inactive lupus nephritis, and 20 lupus patients without nephritis as controls. The study was completed after six months from induction treatment. UKIM-1 was measured by an enzyme linked immunosorbent assay at baseline, three-month follow-up and after complete induction therapy. At baseline, the mean serum creatinine and mean UKIM-1 were 1.7 ±0.7 mg/dL and 10.3 ±1.2 ng/dL, respectively in active LN patients. The mean UKIM-1 levels of complete response and partial response groups were 9.8 ±0.9 ng/mL and 11.3 ±1.0 ng/mL respectively. Based on receiver operating characteristics curve analysis, we found a better diagnostic performance of UKIM-1 to predict response to induction treatment, outperforming conventional biomarkers. The sensitivity and specificity were 84.6% and 85.7 %, respectively at an area under the curve of 0.896 and the best cut-off level was ≤10.6 ng/mL. In conclusion, UKIM-1 performed better than conventional biomarkers in predicting response to treatment of active LN.