Prerenal AKI is caused by?

• A. Obstruction of urinary flow
• B. Decreased blood flow to the kidney
• C. Glomerular damage
• D. Inflammation of renal tubules

Answer: (B)

Prerenal AKI happens when the kidneys aren’t receiving enough blood flow, so filtration falls even though the kidney tissue is intact. This reduced perfusion can come from low blood volume (dehydration, hemorrhage), decreased effective circulating volume (heart failure, severe illness), or systemic factors that drop blood pressure or cardiac output. The crucial point is that the problem is upstream of the kidneys, so the kidney itself isn’t initially damaged.

Obstruction of urinary flow, in contrast, causes postrenal AKI. It blocks urine drainage after the kidneys, leading to back pressure and injury that arises from the post-kidney system, not from reduced perfusion.

Glomerular damage or inflammation of the renal tubules are examples of intrinsic (intrarenal) injury, where the kidney tissue itself is damaged, not simply affected by blood flow.