Complement biomarkers in IgA nephropathy: current insights and clinical relevance.

IgA nephropathy (IgAN) is the most common form of primary glomerulonephritis worldwide and is a major contributor to the global burden of chronic kidney disease. Strong evidence highlights complement activation as a key driver of the disease pathogenesis and its progression. In this regard, the emergence of new therapies targeting the complement system has further increased interest in specific biomarkers that can help in diagnosis, prognosis, and assessment of response to therapy in patients with IgAN. Although complement biomarkers show promising associations with disease severity and prognosis, most remain exploratory and lack adequate validation for routine clinical application. Further research should focus on standardization and prospective multicenter validation of putative biomarkers to facilitate a biomarker-driven approach to the use of complement inhibitors in IgAN. Therefore, this review summarizes a growing body of evidence on the role of complement-related biomarkers in IgAN and discusses their diagnostic and prognostic potential, as well as several limitations for implementation in clinical practice.