Which of these are NOT a renal or intrarenal cause of acute renal failure?

• A. Renal stones
• B. Injury from trauma
• C. Nephrotoxic drugs
• D. Nephrotic infection

Answer: (A)

The main idea is understanding how acute kidney injury is categorized: prerenal (before the kidney), intrinsic renal (within the kidney tissue), and postrenal (obstruction after the kidney). Renal stones block urine flow downstream in the urinary tract, causing a postrenal problem. That means the kidney tissue itself isn’t damaged directly—it's the obstruction that leads to dysfunction. So renal stones are not a renal or intrarenal cause.

In contrast, nephrotoxic drugs injure the kidney tissue itself (intrinsic/renal injury), trauma can directly harm the renal parenchyma or trigger muscle breakdown with kidney-toxic effects, and infections can cause glomerular/intrinsic renal disease. Those are all related to damage inside the kidney, making them intrarenal causes.