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Codeine Toxicity CKD Morphine Accumulation — ESENeph MCQ

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HardChronic Kidney DiseaseCodeine Toxicity CKD Morphine AccumulationESENeph

A 52-year-old with previous Roux-en-Y gastric bypass develops progressive kidney injury. Kidney biopsy shows abundant calcium oxalate crystals within tubules; there is no ethylene-glycol exposure. Which mechanism best explains the renal lesion?

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Correct answer: B — Increased intestinal oxalate absorption from fat malabsorption

After malabsorptive bariatric surgery, unabsorbed fatty acids bind intestinal calcium. Less calcium is then available to bind dietary oxalate, leaving soluble oxalate available for colonic absorption. The resulting enteric hyperoxaluria can cause nephrolithiasis and calcium-oxalate tubulointerstitial injury. Primary hyperoxaluria instead reflects inherited hepatic glyoxylate metabolism defects.

Reference: https://guidelines.ukkidney.org