How Late Is Too Late? Successful Use of Targeted-Release Budesonide in IgA Nephropathy with Estimated Glomerular Filtration Rate <30 mL/min/1.73 m

Introduction: IgA nephropathy (IgAN) is a common cause of chronic kidney disease (CKD) worldwide. However, patients with advanced CKD and significant fibrosis on biopsy have limited treatment options, and clinical trials studying targeted-release budesonide have excluded individuals with low estimated glomerular filtration rate (eGFR). Case Presentation: We report a case of a 36-year-old male with biopsy-proven crescentic IgAN, initially diagnosed 3 years prior, who presented with progressive renal dysfunction and persistent proteinuria despite prior treatment with immunosuppression, including corticosteroids and rituximab. At evaluation, serum creatinine was 2.86 mg/dL with an eGFR of 28 mL/min/1.73 m Conclusion: This case demonstrates clinically meaningful improvement in both proteinuria and renal function following treatment with targeted-release budesonide, despite advanced chronicity but with disease activity and low eGFR, a population that remains underrepresented in clinical trials and prospective studies. Our findings highlight the importance of repeat biopsy and future studies addressing the potential benefit of targeted-release budesonide in select patients with advanced IgAN, who may retain a therapeutically targetable inflammatory component.