Why should NSAIDs be used with caution or avoided in CKD?

• A. They have no renal effects
• B. They improve renal perfusion by dilating efferent arterioles
• C. They cause decreased renal perfusion by constricting afferent arterioles
• D. They only affect the liver

Answer: (C)

Prostaglandins help keep kidney blood flow steady by dilating the afferent arteriole, especially when renal perfusion is challenged. NSAIDs block COX enzymes, which reduces prostaglandin production. With fewer prostaglandins, the afferent arteriole constricts, lowering renal blood flow and glomerular filtration rate. In chronic kidney disease, the kidneys already have reduced reserve and are more dependent on that prostaglandin-driven dilation, so NSAIDs can precipitate or worsen kidney injury. That’s why they should be used with caution or avoided in CKD.

The idea that NSAIDs have no renal effects is incorrect, and the notion that they improve perfusion by dilating the efferent arteriole isn’t accurate—dilation of the efferent arteriole is the action of other drug classes (like ACE inhibitors), not NSAIDs. They also don’t affect only the liver; they have meaningful effects on the kidneys as well.