Oxalate nephropathy following vitamin C intake within intensive care unit

OBJECTIVE: To report a case of acute oxalate nephropathy related to vitamin C intake within the intensive care unit (ICU). DESIGN: Case report. SETTING: ICU and nephrology department of a French university hospital. PATIENT: A 57-year-old woman with septic shock related to Legionella pneumophila pneumonia complicated by acute respiratory distress syndrome and acute kidney injury who required renal replacement therapy for 75 days. MEASUREMENTS AND MAIN RESULTS: A renal biopsy was performed on day 72 because of persistent anuria and because the patient showed characteristic features of severe acute oxalate nephropathy. The only cause identified was vitamin C intake received during hospitalization within the ICU (~ 30 g over 2.5 months). At month 6 after ICU admission, estimated glomerular filtration rate was 24 mL/min/1.73m2. CONCLUSION: Compelling evidence obtained from in-vitro and animal studies suggest that vitamin C, a circulating antioxidant, may be a valuable adjunctive therapy in critically-ill patients. Data from humans are more conflicting. Oxalate, a well-known metabolite of vitamin C, is excreted by the kidneys and can exert a toxic effect on epithelial cells and causes direct tubular damage, and/or it can crystallize within the tubular lumen. This case highlights an under-recognized secondary adverse event from vitamin C given to critically-ill patients. The use of high-dose vitamin C should be prescribed with caution in this population.
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