Ethyl Glucuronide in Alcoholic Beverages

[Problems of ethyl glucuronide use in ethanol consumption diagnosis]

Quantitative determination of ethyl glucuronide (EtG) in different biological objects in recent years has been positioned as one of the most reliable biomarkers of unconditional alcohol consumption. The aim of the study is to summarize the analytical methods of alcohol consumption testing with the use of EtG currently available in domestic and foreign literature and to present a schematic overview of possible errors in reproducibility and interpretation of research on EtG results, which may limit their use in forensic medical practice. The main objective is to increase the reliability and validity of EtG as a marker of ethanol consumption.

Beta-Glucuronidase Activity: Another Source of Ethyl Glucuronide

Numerous classes of endogenous and xenobiotic compounds are conjugated to uridine-5'-diphospho (UDP)-alpha-D-glucuronic acid which is catalyzed by human UDP-Glucuronosyltransferases (UGTs). The resulting beta-D-glucuronides can be hydrolyzed to β-D-glucuronic acid and the corresponding aglycone in a configuration retaining manner by beta-glucuronidases (GUSBs), which are widely distributed in mammalians, microbiota, insects, molluscs, nematodes, fishes and plants. This study investigates GUSBs' activity in the presence of ethanol (0-70% by volume) using different β-D-glucuronides (phenolphthalein-β-D-glucuronide, 4-nitrophenol-β-D-glucuronide, morphine-3-O-β-D-glucuronide, quercetin-3-O-β-D-glucuronide and 1-/2-propyl-β-D-glucuronide) as substrates. It was found that β-D-ethyl glucuronide (EtG), which is a minor UGT-derived metabolite of ethanol in man and one of the most frequently used biomarkers of alcohol consumption today, builds up from all investigated β-D-glucuronides by means of GUSBs in the presence of ethanol. The glucuronyl transfer reaction, which was neither detected in the absence of ethanol nor in absence of GUSBs, is minor at ethanol concentrations which are commonly observed in blood and tiβues after consumption of alcoholic beverages, but predominant at higher concentrations of ethanol. In spite of in vitro characteristics, our observations point to an additional biochemical path and another source of EtG, which should be further evaluated in the context of alcohol biomarker applications. The detection of EtG in several settings independent from of human UGT-metabolism (e.g. EtG post post-collection synthesis in E.coli coli-contaminated urine samples, EtG in wine and ethanolic herbal preparations) can be explained by the described mechanism.

Validation of serotonin transporter mRNA as a quantitative biomarker of heavy drinking and its comparison to ethyl glucuronide/ethyl sulfate: A randomized, double-blind, crossover trial

BACKGROUND

The serotonin transporter (SERT) mRNA was previously reported to be a quantitative and pathophysiology-based biomarker of heavy drinking in 5HTTLPR:LL genotype-carriers treated with ondansetron. Here, we validated the potential use of SERT mRNA for quantitative prediction of recent alcohol consumption (in the absence of treatment) and compared it with the known biomarkers ethyl glucuronide (EtG) and ethyl sulfate (EtS).

METHODS

Binge drinking men and women of European ancestry aged 21 to 65 years were enrolled in a 12-day, in-patient, randomized, double-blind, crossover study, where they were administered three beverage doses (placebo, 0.5 g/kg [0.4 g/kg] ethanol, and 1 g/kg [0.9 g/kg] ethanol for men [women]) individually in three 4-day periods (experiments), separated by minimum 7-day washout period. Diet, sleep, and physical activity were controlled throughout the inpatient experiments. Twenty-nine participants were randomized to receive beverage doses counterbalancing the sequence of treatment and gender within subgroups stratified by SERT genotypes 5HTTLPR:LL+rs25531:AA (LA LA ) versus 5HTTLPR:LS/SS. Peripheral venous blood was collected daily for (1) quantification of SERT mRNA (the primary outcome measure) using qRT-PCR and (2) plasma EtG and EtS levels using tandem mass-spectrometry.

RESULTS

The association between administered beverage dose and SERT mRNA from completers of at least one 4-day experiment (N = 18) assessed by a linear mixed model was not statistically significant. Significant positive associations were found with beverage dose and plasma EtG, EtS and EtG/EtS ratio (β = 5.8, SE = 1.2, p < 0.0001; β = 1.3, SE = 0.6, p = 0.023; and β = 3.0, SE = 0.7, p < 0.0001, respectively; the C-statistics for discriminating outcomes were 0.97, 0.8, and 0.92, respectively). Additionally, we observed a sequence effect with a greater placebo effect on SERT mRNA when it was administered during the first experiment (p = 0.0009), but not on EtG/EtS measures.

CONCLUSION

The findings do not validate the use of SERT as a biomarker of heavy drinking. Larger and more innovative studies addressing the effects of placebo, race, gender, and response to treatment with serotonergic agents are needed to fully assess the utility of SERT as a biomarker of heavy and binge drinking.

Positive findings of ethyl glucuronide in hair of young children from families with addiction background

AIMS

Small children are expected to be abstinent from alcohol, and children's hair is frequently used as the blank matrix for calibration of the alcohol consumption marker ethyl glucuronide (EtG). The basal EtG concentrations of total abstainers were described to be 0.3-2.1 pg/mg (Pirro et al. 2013). It is examined whether this assumption is valid for children from families with addiction background.

METHODS

In a social support system for families with drug and/or alcohol addicted parents, 161 hair samples from 126 children (age 1-14 years, hair segment 0-3 cm) were analyzed for EtG by a validated LC-MS/MS method (LOD 0.56 pg/mg, LLOQ 2.3 pg/mg). For comparison, ethyl palmitate (EtPa) was measured and hair samples from parents were included. EtG ≥ 3 pg/mg was considered as an alarming result for children.

RESULTS AND DISCUSSION

EtG concentrations between 3.0 and 42.6 pg/mg (mean 9.55 pg/mg, median 6.40 pg/mg) were measured for 25 samples (15.5%, age 22 × 1-5 years, 3 × 9-11 years). Elevated EtPa (0.15-0.46 ng/mg) was found in 6 samples and cocaethylene (0.02-0.07 ng/mg) was detected in 5 samples with high cocaine findings. Hair results of one or both parents indicated drug abuse in 12 from 14 cases (85.7%) if both parents were tested.

CONCLUSION

Although accidental or voluntary intake of alcoholic beverages cannot be excluded, the external contamination of children's hair by EtG-containing wine and sweat or urine of the alcohol abusing parents is assumed to be the most probable explanation for the positive EtG results in hair of 1-5-year-old children.