Why should NSAIDs be used cautiously in patients with renal impairment?

• A. They have no effect on renal function
• B. They can cause dehydration
• C. They can improve renal perfusion
• D. They can reduce renal perfusion and worsen renal function

Answer: (D)

NSAIDs work in the kidney by blocking prostaglandin production. Prostaglandins normally dilate the afferent arteriole to help maintain renal perfusion and glomerular filtration, especially when the kidneys are stressed or volume-depleted. In renal impairment, the kidney relies even more on this prostaglandin-mediated dilation. By inhibiting prostaglandins, NSAIDs cause constriction of the afferent arteriole, reduce renal blood flow, and lower GFR, which can worsen kidney function or trigger acute kidney injury. So the best choice is that they can reduce renal perfusion and worsen renal function. The other statements aren’t correct because NSAIDs do affect renal function, they don’t improve perfusion, and dehydration isn’t the primary mechanism here.