Interference of high dose ascorbate in blood gas, point-of-care, and automated clinical chemistry assays.

Ascorbic acid (AA) has been under investigation for a variety of therapeutic indications, including cancer treatment and sepsis. New investigational treatments utilize much higher concentrations than historical studies, leading to uncertainty about the effects on clinical testing platforms. Published work indicates AA interferes with lipid and point-of-care glucometer measurements, however a comprehensive evaluation of potential interference at these higher concentrations with a unified experimental design is lacking. Additionally, many of the published studies use unbuffered AA spiked into blood which may cause spurious results due to pH disturbances. The objective of this study is an evaluation of high concentrations of sodium ascorbate interference on various analysis platforms. Sodium ascorbate was spiked into residual patient serum at 0-200 mg/dL. These samples were analyzed in triplicate on the Abbott ARCHITECT c8000 clinical chemistry and i2000SR immunoassay analyzers for a large menu of analytes. Whole blood studies were conducted at 0-200 mg/dL sodium ascorbate on the Nova STAT PROFILE pHOX Ultra system co-oximetry assays, Abbott i-STAT 1 System using the i-STAT Chem8+ cartridge, and a Roche Accu-Chek Inform II System glucometer. Assay interference by ascorbate was detected for lactate, lipase, cholesterol, triglycerides, and several glucose assay platforms. This multi-platform study at high concentrations of ascorbate for a variety of clinical chemistry assays will be of use to laboratorians and clinicians who have patients undergoing these treatments.