IgG4-related kidney disease: treatment standard

IgG4-related disease is a systemic, immune-mediated, fibro-inflammatory condition that can affect virtually any organ. IgG4-related kidney disease represents one of the most clinically relevant manifestations and encompasses a spectrum of renal manifestations, including IgG4-related tubulointerstitial nephritis, membranous nephropathy, and obstructive uropathy secondary to retroperitoneal fibrosis. The diagnosis remains challenging and requires integration of clinical and laboratory findings, along with imaging, and histopathology, as no single biomarker is sufficiently sensitive or specific. Although systemic immunosuppressive therapies largely overlap across manifestations, the practical management differs substantially between parenchymal kidney disease and retroperitoneal fibrosis, particularly with regard to mechanisms of kidney injury, the need for interventional procedures, treatment goals, and monitoring strategies. Glucocorticoids are the cornerstone of induction therapy and typically provide rapid clinical responses; however, the chronic-relapsing course of IgG4-related disease and the burden of glucocorticoid-related toxicity have prompted investigation in steroid-sparing strategies. Conventional immunosuppressive agents have been used with controversial results, whereas B-cell-targeting therapies, particularly rituximab, have demonstrated high efficacy in both induction and maintenance settings. Management should ultimately be individualised, taking into account the pattern of renal involvement, organ dysfunction, and likelihood of reversibility. In patients with obstructive uropathy due to retroperitoneal fibrosis, interventional procedures may be required alongside immunosuppressive therapy. Long-term monitoring is essential because of the relapsing nature of the disease and the potential for chronic kidney disease. This Treatment Standard provides a practical, nephrology-oriented framework for the diagnosis, treatment and follow-up of IgG4-related kidney disease, integrating current evidence with emerging insights from immunopathogenesis and clinical trials.