Your patient with kidney stones develops acute kidney injury and hydronephrosis. What is the best treatment for this postrenal kidney injury?

A. Remove offending medication is incorrect because this approach applies to intrarenal causes of AKI, such as nephrotoxic medications like NSAIDs, aminoglycosides, or contrast dyes. While stopping these drugs can prevent further kidney damage, it does not address the actual cause of postrenal AKI, which is a mechanical blockage in the urinary tract. B. Correct hypovolemia with IV fluids is incorrect because this intervention targets prerenal AKI, where reduced kidney perfusion due to dehydration, blood loss, or hypotension is the issue. In postrenal AKI, the problem is urine flow obstruction, not perfusion. Administering fluids alone will not restore kidney function and may even worsen complications if hydronephrosis is present. C. Remove obstruction is correct because postrenal AKI occurs when urine cannot exit the kidneys due to a blockage, leading to back pressure, hydronephrosis, and impaired filtration. In this case, kidney stones are the obstructing factor. Effective management requires rapid relief of the obstruction through interventions such as stone removal, ureteral stenting, catheterization, or surgery, depending on the location and size of the obstruction. Relieving the obstruction restores urine flow, reduces pressure on the kidneys, prevents permanent damage, and decreases the risk of infection or electrolyte imbalances. D. Ask about medication history is incorrect because although understanding a patient’s medication use is important for overall kidney health and identifying nephrotoxic drugs, it does not treat the obstruction causing postrenal AKI. This step is supportive rather than curative in this acute scenario.