The Effects of Intravenous Vitamin C on Point-of-Care Glucose Monitoring

Abstract

Ascorbic acid (vitamin C) decreases systemic inflammation and lowers fluid requirements after thermal injury; therefore it has been adopted in many burn centers as an adjunct to resuscitation. However, recent concerns have been expressed over clinically significant hypoglycemic events caused by vitamin C interference with the point-of-care (POC) glucose measurements. This case series presents a direct comparison of POC and laboratory reference glucose values in the patients receiving vitamin C infusion. Vitamin C was administered at 66 mg/kg/hour in seven patients with burns >30% TBSA. The baseline characteristics and burn characteristics were recorded. POC glucose measurements were made with a commonly used hand-held device, and the laboratory values were obtained using standard spectrophotometric methods. POC and laboratory glucose values drawn within the same hour were compared. Hemoglobin, which is known to cause interference in POC testing, was also recorded. All the patients demonstrated falsely elevated POC glucose values during and/or immediately after the infusion period, with discrepancies ranging from 10 to 200 mg/dl. These findings were irregular, unpredictable and unrelated to hemoglobin levels. The findings suggest an idiosyncratic reaction that cannot be easily corrected at the bedside using mathematical equations. POC glucose monitoring should be avoided during and after vitamin C therapy.

Accuracy of Point‐of‐Care Blood Glucose Level Measurements in Critically Ill Patients with Sepsis Receiving High‐Dose Intravenous Vitamin C

“…Multiple cases of inaccurate POC BG level measurements in patients receiving high‐dose IV vitamin C were reported, but none of these patients had sepsis. The indications for vitamin C in these studies included malignancy, diabetic retinopathy, and burn resuscitation.…”

“…A retrospective review of five patients receiving vitamin C demonstrated significantly higher mean POC BG levels (225 ± 71 mg/dl) compared with mean laboratory BG levels (138 ± 41 mg/dl) . Additionally, a case series involving seven burn patients reported a difference in POC BG and laboratory BG levels ranging from 10–200 mg/dl . In some cases, the interference appeared to continue well beyond the discontinuation of vitamin C therapy …”

“…Another potential confounder with vitamin C is its potential to interfere with point‐of‐care (POC) glucose testing and associated interventions to maintain glycemic control. Literature involving 15 patients in a variety of settings (burns, cancer, diabetes mellitus) receiving IV vitamin C in doses of 10 g/day or higher described artifactually high POC blood glucose (BG) level measurements ranging from 10–280 mg/dl above laboratory test results . Unpublished data suggest that this degree of artifact is not apparent with vitamin C doses used in patients with sepsis .…”

“…Literature involving 15 patients in a variety of settings (burns, cancer, diabetes mellitus) receiving IV vitamin C in doses of 10 g/day or higher described artifactually high POC blood glucose (BG) level measurements ranging from 10-280 mg/dl above laboratory test results. [8][9][10][11][12] Unpublished data suggest that this degree of artifact is not apparent with vitamin C doses used in patients with sepsis. 13 Verification of these findings is important to avoid inappropriate interventions based on erroneous POC BG level measures.…”

A Retrospective Analysis of Clinical Laboratory Interferences Caused by Frequently Administered Medications in Burn Patients

“…An example of burn specific pharmacotherapy interfering with laboratory testing has been recently recognized during high dose ascorbic acid therapy. [3,4] During acute burn shock patients are resuscitated using the Parkland formula. [5,6] Patients who do not respond to standard resuscitation protocols are at risk of volume overload, which has been shown to lead to extremity or abdominal compartment syndrome as well as acute respiratory distress syndrome.…”