Urine KIM-1 as Predictor of Renal Histopathology and Treatment Response in Lupus Nephritis Patients

Author(s): Mamun Chowdhury Raju, Rana Mokarram Hossain, A. H. Hamid Ahmed, Muhammad Nazrul Islam, Md. Omar Faroque, Md Bedar Uddin, S.M. Remin Rafi, Anjuman Ara Daisy, Nur Jahan, Noureen Amin

Introduction: Lupus nephritis is one of the most severe complications of systemic lupus erythematosus (SLE) and typically develops within five years of an SLE diagnosis in 50%-60% of patients. Lupus nephritis is a major predictor of prognosis and a significant contributor to morbidity and mortality in SLE. Renal biopsy is the gold standard for diagnosing lupus nephritis patients. However, its invasive nature and associated risks limit its use, highlighting the need for non-invasive biomarker like Kidney Injury Molecule-1 (KIM-1). Present study aimed to assess urine KIM- 1 as predictors of renal histopathology and treatment response in lupus nephritis patients. Materials & Methods: This prospective observational study was conducted in the Nephrology department at Bangabandhu Sheikh Mujib Medical University (BSMMU), Dhaka, from March 2023 to August 2024, involving adult patients (age ≥ 18 years) diagnosed with SLE and lupus nephritis. Using convenience sampling, 52 respondents were enrolled. Ethical approval was obtained from the Institutional Review Board (IRB) of BSMMU. Renal biopsies and urine samples were collected for analysis, and patients were followed up at six months. Results: The study population had a mean age of 28.1 years. The female predominance was 92.3%. The mean BMI was 24.2 kg/m². Hypertension was present in 46.2% of respondents, anemia in 30.8%, edema in 59.6%, and proteinuria in 48.1% (++), and 34.6% (+++). Histologically, 57.7% were classified as Class IV lupus nephritis, and 17.3% as Class III. Hydroxychloroquine was administered to 100% of respondents, cyclophosphamide with corticosteroids to 61.5%, MMF with corticosteroids to 23.1%, and corticosteroids alone to 15.4%. Complete response was achieved by 67.3%, partial response by 28.8%, and no response by 3.8%. At baseline, Class IV lupus nephritis patients had the highest mean urine KIM-1 levels (672.7 ± 504.0 ng/mL), which decreased after six months but remained highest (231.6 ± 191.4 ng/mL). The proliferative group had significantly higher mean urine KIM-1 levels than the non-proliferative group at both baseline and six months. Mean Urine KIM-1 level was significantly (p < 0.05) lower in respondents with a complete response compared to those with partial or no response, both at baseline and after six months. Statistically significant differences in mean serum creatinine, serum albumin, and urinary PCR levels were observed between response groups. Conclusion: Urine KIM-1 levels significantly correlate with disease severity and renal function markers, highlighting its clinical utility. Future research should validate urine KIM-1 as a biomarker and explore its potential in guiding treatment decisions.

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