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Dietary Oxalate Nephropathy Iced Tea — ESENeph MCQ

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ModerateAcute Kidney InjuryDietary Oxalate Nephropathy Iced TeaESENeph

A 55-year-old man presents with AKI and a renal biopsy showing crystal deposits within tubular lumens that are birefringent and rhomboid-shaped under polarised light. He has been drinking large amounts of iced tea daily for several years. What is the diagnosis?

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Correct answer: A — Oxalate nephropathy from excessive dietary oxalate (iced tea contains high oxalate concentrations)

Excessive consumption of oxalate-rich foods/beverages can cause secondary oxalate nephropathy. Black tea is very high in oxalate, and drinking large volumes (>1 L/day) of iced tea has been reported to cause AKI from intratubular calcium oxalate crystal deposition. The birefringent rhomboid/envelope-shaped crystals on biopsy are characteristic of calcium oxalate. Other dietary causes include excessive spinach, rhubarb, starfruit, and high-dose vitamin C. Management involves stopping the offending intake, hydration, and dietary counselling. CKD may result from permanent tubular damage.

Reference: Syed et al 2015 – Iced Tea Oxalate Nephropathy; KDIGO 2012 – AKI