Q. A 38-year-old woman with a history of systemic lupus erythematosus (SLE) presents with a 3-day history of malaise, nausea, and decreased urine output. She has no significant medical history except for SLE, which was diagnosed eight years ago. Her medications include hydroxychloroquine, mycophenolate mofetil, and prednisone. On examination, she appears dehydrated. Her blood pressure is 170/100 mm Hg, heart rate is 110 beats/min, respiratory rate is 22/min, and temperature is 98°F. There is diffuse abdominal tenderness with no rebound or guarding. Laboratory findings reveal a serum creatinine of 3.2 mg/dL, potassium of 6.0 mmol/L, bicarbonate of 16 mmol/L, and glucose of 200 mg/dL. What is the most likely cause of this patient's renal failure?