[Autoimmune hemolytic anemia complicated with acute kidney injury and tubulopathy due to hemoglobin casts].

A 62-year-old male patient was admitted for close monitoring of anemia (hemoglobin level, 8.2 g/dl). Hemolytic anemia was observed; however, the direct antiglobulin test (DAT) result (standard tube method) was negative. Nevertheless, autoimmune hemolytic anemia (AIHA) was still suspected; therefore, a DAT (Colum method) and quantifying levels of red-blood-cell bound immunoglobulin G were performed, resulting in a definite diagnosis of warm AIHA. The patient also had an acute kidney injury (AKI) from the time of admission, which was poorly improved by supplemental fluids therapy alone. Therefore, renal biopsy was performed. Renal biopsy revealed acute tubular injury due to hemoglobin columns, and a diagnosed AKI caused by hemolysis due to AIHA. Following the definitive diagnosis of AIHA, the patient was treated with prednisolone, and after approximately 2 weeks, the anemia and nephropathy completely improved, which is maintained to this day. We report this case as a rare case of AKI induced by hemolysis of AIHA and a successful case of renal salvage by early administration of steroid.