In Reply Dr Hager and colleagues raise 2 important issues regarding use of high-dose intravenous vitamin C: recognition of hypoglycemia and factitious hyperglycemia that may lead to inappropriate use of insulin. Bedside point-of-care glucose measurements have emerged as the standard of care in many intensive care units, and these devices will record false elevations of blood glucose as intravenous infusion of vitamin C leads to high plasma levels. Using point-of-care devices in patients receiving intravenous vitamin C prevents recognition of hypoglycemia and may lead to inappropriate use of insulin. Interference with devices by vitamin C begins to occur with plasma levels of approximately 250 μmol or greater. As noted by Hager and colleagues, plasma levels of 50 mg/kg may achieve plasma concentrations of greater than 5000 μmol. We agree that in the CITRIS-ALI trial,1 delay in processing and freezing plasma for vitamin C quantification likely led to lower recorded results. In a previous trial performed at Virginia Commonwealth University, plasma was immediately processed, which led to less oxidation of vitamin C, resulting in higher plasma concentrations.2 In the CITRIS-ALI trial, point-of-care glucose measurements were stopped at the onset of vitamin C infusion and were not reinstituted for 36 hours following cessation of infusion.1 During that time, only central laboratory glucose measurements were permitted.
Fowler AA, Fisher BJ, Kashiouris MG. Vitamin C for Sepsis and Acute Respiratory Failure—Reply. JAMA. 2020;323(8):792–793. doi:10.1001/jama.2019.21987
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