Acute Kidney Injury Associated with Minimal Change Nephrotic Syndrome in an Elderly Patient Successfully Treated with both Fluid Management and Specific Therapy Based on Kidney Biopsy Findings.

Oliguric acute kidney injury (AKI) with minimal change nephrotic syndrome (MCNS) has long been recognized. Several mechanisms such as hypovolemia due to hypoalbuminemia and the nephrosarca hypothesis have been proposed. However, the precise mechanism by which MCNS causes AKI has not been fully elucidated. Herein, we describe an elderly patient with AKI caused by MCNS who fully recovered after aggressive volume withdrawal by hemodialysis and administration of a glucocorticoid. A 75-year-old woman presented with diarrhea and oliguria, and laboratory examination revealed nephrotic syndrome (NS) and severe azotemia. Fluid administration had no effect on renal dysfunction, and hemodialysis was initiated. Her renal function improved upon aggressive fluid removal through hemodialysis. Renal pathological findings revealed minimal change disease with faint mesangial deposits of IgA. After administration of methylprednisolone pulse therapy followed by oral prednisolone, she achieved complete remission from NS. The clinical course of this case supports the nephrosarca hypothesis regarding the mechanism of AKI caused by MCNS. Furthermore, appropriate fluid management and kidney biopsy are also important in elderly patients with AKI caused by NS.