An 80-year-old woman with a history of hypertension, coronary artery disease, and severe osteoarthritis is admitted for acute kidney injury. Her medications include lisinopril, aspirin, and daily ibuprofen. Labs show serum creatinine increased from 1.0 mg/dL to 3.2 mg/dL, hyperkalemia, and a non-anion gap metabolic acidosis. Urine studies reveal a FENa of 0.3%. What is the most likely cause of her acute kidney injury?
✓ Correct Answer: Option C
The combination of an ACE inhibitor (lisinopril) and an NSAID (ibuprofen) can synergistically impair renal perfusion, especially in elderly patients with underlying cardiovascular disease. The low FENa (<1%) is classic for prerenal azotemia.