Nintedanib-induced Glomerular Microangiopathy after Long-term Nintedanib Administration Presenting with Nephrotic Syndrome

We herein report a rare case of nintedanib-induced glomerular microangiopathy (GMA) in a 77-year-old woman with idiopathic pulmonary fibrosis. The patient developed nephrotic-range proteinuria (5.9 g/gCr) after 29 months of nintedanib therapy. A kidney biopsy confirmed GMA, which was characterized by endothelial injury without immune complex deposition. The discontinuation of nintedanib led to a significant reduction in proteinuria. This case demonstrates that nintedanib-induced GMA can manifest after long-term use. Given the potential for a global underdiagnosis, regular urinalysis testing is therefore essential for the early detection of irreversible renal damage, particularly in elderly patients.