Nonsteroidal anti-inflammatory drugs (NSAIDs) affect renal function by:

• A. Decreasing risk
• B. No effect
• C. Increasing risk of renal impairment
• D. Improving renal perfusion

Answer: (C)

NSAIDs impair renal function by blocking cyclooxygenase enzymes and reducing prostaglandin production in the kidney. Prostaglandins such as PGE2 and PGI2 normally dilate the afferent arteriole and help maintain glomerular filtration when kidney perfusion is compromised (for example, during dehydration, volume depletion, heart failure, or chronic kidney disease). By inhibiting these prostaglandins, NSAIDs cause constriction of the afferent arteriole, lowering renal blood flow and the glomerular filtration rate, which raises the risk of renal impairment or acute kidney injury. This risk is especially notable in patients who are volume-depleted or on other nephrotoxic or hemodynamically active drugs (like diuretics or certain antihypertensives).