Serum-Ethanol Determination: Comparison of Lactate and Lactate Dehydrogenase Interference in Three Enzymatic Assays

Abstract

Gas chromatography is considered to be the reference method for ethyl alcohol determination. However, enzymatic ethanol assays have been developed for use in the clinical laboratory by several commercial vendors. Essentially, these assays utilize the oxidation of ethyl alcohol to acetaldehyde with concurrent reduction of nicotinamide adenine dinucleotide (NAD) to NADH while monitoring the increase in absorbance at 340 nm. The increase in absorbance is theoretically proportional to the ethanol concentration in the sample. Previously, several authors reported that increased concentrations of lactate and lactate dehydrogenase (LDH) can cause false-positive results with certain enzymatic ethyl alcohol assays. In the present investigation, we further studied the interference of lactate and LDH in three enzymatic assays. Apparent ethyl alcohol concentrations in serum spiked with lactate and LDH, as well as patient and autopsy samples, were determined by the Syva, Abbott, and Roche enzymatic assays and by gas chromatography. The effect of coenzyme depletion on the rate of reaction and the interference of hemolysis were also investigated. Based on our results we suggest that coenzyme depletion plays a major role in the severity of the false-positive ethyl alcohol result, and the interference from hemolysis has a negligible effect on these results. We also confirm the previous studies in showing that elevated serum-lactate and LDH concentrations can result in varying degrees of false-positive ethyl alcohol concentrations in the three enzymatic assays. This should be taken into consideration in the management of patients in a tertiary care medical center.

Death Following Recreational Use of Designer Drug “Bath Salts” Containing 3,4-Methylenedioxypyrovalerone (MDPV)

“…Most likely the serum ethanol levels quantified via the serum ethanol assay (Beckman UniCel DxC, Beckman Coulter Inc, Brea, CA) were falsely elevated due to interference from the patient's profoundly elevated lactate dehydrogenase (LDH) (11,108 IU/L, 19 h after presentation) and lactate levels (10.7 mmol/ L, 19 h after presentation). This interference of LDH and lactate with serum ethanol determination has been described with multiple instruments/assays, including the methodology used to measure ethanol in this case [26][27][28]. These assays are based on the conversion of ethanol to acetylaldehyde by alcohol dehydrogenase reducing NAD to NADH in the process, which is quantitated by absorbance at 340 nm due to NADH formation.…”

Peginterferon alpha‐2b plus ribavirin vs interferon alpha‐2b plus ribavirin for chronic hepatitis C in HIV‐coinfected patients

“…HIV RNA was determined by a commercial NASBA assay (Organon Teknica, Bostel, The Netherlands), with a detection limit of 80 copies/mL. CD4+ T cells were determined by flow cytometry (FACScan; Becton Dickinson, Erembodegem Aslst, Belgium), and blood lactate levels were analyzed as described [19].…”

Evaluation of Potential Lactate/Lactate Dehydrogenase Interference with an Enzymatic Alcohol Analysis

“…Although it had been suggested that lactate alone can interfere with the ADH-based assay by "cross-reaction," lactate, as noted previously (8), is not an effective substrate for ADH. It is, however, reasonable to suggest that the combination of high levels of both lactate and LDH can, in the presence of the excess NAD + in the assay, produce NADH and thereby cause a falsely elevated ethanol reading as reported by Nine et al (10), who also demonstrated the differential susceptibility of specific assays to this interference. Serum lactate increases rapidly after death, even in the early postmortem period (11).…”