How do NSAIDs affect renal function and GI safety, and which patient factors increase risk?

• A. Decrease gastric acid
• B. Increase renal perfusion
• C. Inhibit aldosterone secretion
• D. Inhibit prostaglandins reducing renal perfusion; risk for AKI and GI bleeding; higher risk in elderly, CKD, dehydration, heart failure, concurrent anticoagulants

Answer: (D)

Prostaglandins help protect both the kidneys and the stomach by promoting vasodilation of the renal afferent arteriole and by enhancing mucosal defenses in the GI tract. NSAIDs block prostaglandin synthesis, which reduces renal perfusion and lowers the glomerular filtration rate, increasing the risk of acute kidney injury, especially when the kidneys are already stressed by dehydration, volume depletion, chronic kidney disease, or heart failure. At the same time, decreased prostaglandin production compromises the gastric mucosal barrier, reducing protective mucus and bicarbonate and elevating the risk of ulcers and GI bleeding.

Factors that heighten this risk include older age (reduced renal reserve and mucosal defenses), chronic kidney disease, dehydration or low volume status, heart failure (lower effective renal perfusion), and concurrent anticoagulant therapy (which raises GI bleeding risk if mucosal injury occurs). These elements amplify both the renal and GI dangers posed by NSAID use.