Which scenario most likely indicates prerenal AKI?

• A. Severe dehydration causing reduced renal perfusion
• B. Nephrotoxic drug-induced tubular injury
• C. Acute glomerulonephritis
• D. Urinary tract obstruction causing post-renal AKI

Answer: (A)

Prerenal AKI happens when the kidneys themselves are fine, but they aren’t getting enough blood flow. Severe dehydration drops the circulating volume and renal perfusion, so the glomeruli don’t filter effectively and the GFR falls. This scenario fits a perfusion problem rather than direct kidney injury, which is why it’s the best match for prerenal AKI. In this situation the body often preserves kidney function by boosting reabsorption of sodium and water, leading to a low urine sodium concentration and a high BUN-to-creatinine ratio, and the kidney function can improve quickly once fluids are restored.

The other scenarios involve intrinsic kidney injury or obstruction. Nephrotoxic drugs injure tubular cells inside the kidney, acute glomerulonephritis damages the glomeruli, and a urinary tract obstruction causes a post-renal AKI through back-pressure effects. These are not primarily about reduced perfusion, so they don’t represent prerenal AKI.