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Acute Phosphate Nephropathy — ESENeph MCQ

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ModerateAcute Kidney InjuryAcute Phosphate NephropathyESENeph

A 42-year-old woman develops acute phosphate nephropathy after using oral sodium phosphate bowel preparation for colonoscopy. Her creatinine rises from 90 to 320 umol/L. Biopsy shows tubular calcium phosphate deposits. Her baseline eGFR was normal. What are the key risk factors for this complication?

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Correct answer: E — Older age, pre-existing CKD, volume depletion, ACEi/ARB use, and high phosphate load

Acute phosphate nephropathy occurs when oral sodium phosphate preparations cause massive phosphate absorption, leading to calcium phosphate crystal deposition in renal tubules. Risk factors include: older age (>55), pre-existing CKD (even mild), volume depletion, ACEi/ARB or diuretic use (reduced renal blood flow), and excessive phosphate load. The condition can cause irreversible CKD. Polyethylene glycol-based preparations are preferred in at-risk patients. FDA issued a safety warning in 2008.

Reference: Markowitz et al 2005 – Acute Phosphate Nephropathy; FDA 2008 Safety Warning