Does the standard proteinuria cut-off for renal biopsy in lupus nephritis as per the current guidelines hold good for Asian population? A single-centre study from South India

Introduction Current rheumatology and nephrology society guidelines in lupus nephritis do not recommend renal biopsy for proteinuria of less than 500 mg/24 h. This might lead to a significant delay in the early diagnosis of lupus nephritis. Aim The main aim of this study is to determine the nature of renal lesions in patients with low-grade proteinuria and to analyze the predictors for clinically significant lupus nephritis. Methods This was a single-center, retrospective study. All consecutive patients of lupus nephritis, with low-grade proteinuria (200 mg to 500 mg/24 h) undergoing renal biopsy were enrolled in this study. The renal biopsies were classified into significant lesions (Class III/IV/V) and non-significant lesions (Class I and II). Treatment naïve groups and treatment-modified groups were analyzed separately. Predictive factors for significant renal lesions were determined by univariate and multivariate analysis. Results We identified 183 patients of lupus with proteinuria between 200 and 500 mg / 24 h. Mean (SD) age was 30.2 (11.39) years with 167 (91.2%) of them being females. The mean (SD) baseline proteinuria was 351.03 (98.1) mg/24 h 85 patients (46.5%) had proliferative lupus nephritis where whereas 17 patients (9.3%) had membranous nephropathy. Crescents and fibrinoid necrosis were seen in 10 (5.46%) and 24 (13.11 %) patients respectively. Isolated proteinuria without any other sediments was seen in 95 patients (51.9%) of which 29 patients had proliferative lupus nephritis. Elevated Anti-double stranded DNA (anti-dsDNA), low C3, low C4 and the presence of urinary sediments were significantly associated with significant renal lesions in biopsy. Conclusion Significant renal lesions were seen in around half of the patients with low-grade proteinuria underscoring the importance of performing a renal biopsy in this set of patients. Low C3 and C4, urinary sediments, and elevated anti-dsDNA were predictors for significant renal lesions.