SYSTEMATIC REVIEW article
Front. Nephrol.
Sec. Glomerular disease
Lower Proteinuria Is Better For Patients With IgA Nephropathy: A Systematic Review
Provisionally accepted
- 1Vertex Pharmaceuticals (United States), Boston, United States
- 2Maple Health Group, New York, United States
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Background: Proteinuria is a well-established and recommended biomarker for disease activity in patients with IgAN. In the most recent version of the KDIGO guideline, the target level of proteinuria changed from < 1.0 g/day to < 0.5 g/day. The objective of this systematic literature review (SLR) is to identify, synthesize, and critically evaluate the evidence from peer-reviewed publications that inform the significance of achieving different proteinuria levels. Methods: We searched PubMed and Embase (2005-2025) for studies in adult patients diagnosed with IgAN that examined the relationship between proteinuria measured by any method (e.g., uPCR, 24-hour protein excretion) and key kidney outcomes. The review used an a priori protocol following established methodological guidance for systematic reviews. Additionally, the quality of all studies included in the SLR was assessed based on standardized appraisal tools. The evidence was narratively synthesized reporting frequencies and percentages. Results: Twenty-one unique studies were included (representing 13,006 patients with IgAN). The studies captured in the SLR were mostly observational and they encompassed diverse patient populations, timing of proteinuria assessment, methods of proteinuria measurement and classification, and clinical management strategies, reflecting real-world heterogeneity in IgAN. Despite the differences in individual study methods, results across studies consistently found that lower proteinuria was associated with better kidney outcomes. Specifically, it was clearly established that <0.5 g/day achieved better outcomes than higher proteinuria thresholds. Conclusion: The evidence identified in this SLR affirms the updated KDIGO recommendation to achieve at least a proteinuria level of < 0.5 g/day. Registration: PROSPERO registration number: CRD420251062821
Keywords: IgA, nephropathy, IgAN, Proteinuria, Kidney failure, Systematic review
Received: 10 Oct 2025; Accepted: 05 Dec 2025.
Copyright: © 2025 Shah, Maski, Egbuna, Longstaff, Stricker-Shaver and Barber. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Ankit Shah
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