Authors of a systematic review and meta-analysis of 23 studies involving 15,289 patients found that low-grade proteinuria—typically 0.5 to 1.0 g/day or g/g—was associated with a significantly greater risk of adverse kidney outcomes in patients with IgA nephropathy. Compared with minimal proteinuria, low-grade proteinuria at baseline was associated with a 73% higher risk of outcomes such as substantial eGFR decline, kidney failure, or kidney replacement therapy. The findings were consistent across multiple measures of proteinuria and study populations.
Proteinuria over time appeared particularly important. Low-grade time-averaged proteinuria was associated with nearly three times the risk of adverse kidney outcomes and a faster annual decline in eGFR, suggesting that cumulative proteinuria exposure may be more informative than a single measurement at diagnosis. The authors concluded that proteinuria below 1.0 g/day should not necessarily be considered low risk and that closer monitoring and efforts to maintain proteinuria below 0.5 g/day may help inform management. Because all included studies were observational, however, the findings cannot establish causality and should be interpreted alongside differences in study definitions and treatments.
Reference: Yamaguchi Y, Kosugi T, Sasaki T, et al. The Association between Low-Grade Proteinuria and Adverse Kidney Outcomes in IgA Nephropathy: A Systematic Review and Meta-Analysis. Clin J Am Soc Nephrol. 2026 Apr 1;21(4):615-625. doi: 10.2215/CJN.0000000952.
