In which scenario is NSAID-induced reduction in renal perfusion least likely to occur?

• A. Volume depletion
• B. Chronic kidney disease
• C. Volume replete state
• D. Acute kidney injury

Answer: (C)

NSAIDs reduce renal perfusion by blocking prostaglandin-mediated dilation of the afferent arteriole, which helps sustain GFR when kidney perfusion is challenged. In volume depletion or states with reduced effective circulating volume, the kidney relies more on prostaglandins to maintain blood flow, so NSAIDs more readily drop GFR and can trigger or worsen kidney injury. In chronic kidney disease and acute kidney injury, the kidneys are already stressed and more vulnerable to decreases in perfusion from prostaglandin inhibition. In a volume replete state, perfusion pressure is adequate and autoregulatory mechanisms keep the afferent arteriole flow stable, so blocking prostaglandins has a much smaller effect. Therefore, the reduction in renal perfusion from NSAIDs is least likely when the patient is volume replete.