Acute Kidney Injury USMLE Step 1 Practice Question

A 41-year-old man with a 6-month history of poorly controlled hypertension presents to the emergency department with severe frontal headache, dyspnea, and blurred vision that began acutely 4 hours ago. His wife reports he has not been taking his antihypertensive medications. Physical examination reveals bilateral retinal hemorrhages and papilledema. Vital signs: BP 218/138 mmHg, HR 106/min, RR 24/min, SpO2 93% on room air. Laboratory studies show serum creatinine 3.1 mg/dL (baseline 1.0 mg/dL obtained 2 months prior), BUN 68 mg/dL, platelets 84,000/μL (baseline 280,000/μL), and hemoglobin 9.2 g/dL (baseline 14.5 g/dL). Peripheral blood smear demonstrates schistocytes. Urinalysis shows 3+ proteinuria and RBC casts. Chest radiograph is clear without pulmonary edema. Renal artery stenosis is excluded by duplex ultrasound. Which of the following best explains this patient's acute kidney injury?