Which of the following is NOT a pre-renal cause of AKI?

The selection of obstruction as the answer highlights an important distinction in the causes of acute kidney injury (AKI). Pre-renal causes of AKI typically arise from factors that impair blood flow to the kidneys, leading to decreased glomerular perfusion. Obstruction, on the other hand, falls under the category of post-renal causes, where the issue lies in a blockage that prevents urine from flowing out of the kidneys. This obstruction can occur anywhere along the urinary tract, leading to back pressure and potential kidney damage, but it does not originate from a pre-renal mechanism.

In contrast, volume depletion, impaired cardiac function, and severe dehydration all represent scenarios where there is inadequate blood supply to the kidneys, which can result from decreased circulating volume, compromised heart function, or loss of fluids, respectively. These conditions undermine renal perfusion, making them classic examples of pre-renal causes of AKI. Understanding these categories helps in recognizing the underlying mechanisms of kidney injury and tailoring appropriate interventions.