PLE-2289

A 68-year-old male with diabetic nephropathy, presenting with a creatinine level of 2.4, experienced a sudden increase in creatinine to 9 mg/dl. There is no history of blood loss or diarrhea. Additionally, the patient has been experiencing anemia and low back pain for the past 6 months. A 24-hour urine protein test revealed proteinuria of 10g/day. The urine dipstick test, however, showed a negative result.