Assessment of ethyl sulphate in hair as a marker for alcohol consumption using liquid chromatography-tandem mass spectrometry

Biomarkers of moderate alcohol intake and alcoholic beverages: a systematic literature review

The predominant source of alcohol in the diet is alcoholic beverages, including beer, wine, spirits and liquors, sweet wine, and ciders. Self-reported alcohol intakes are likely to be influenced by measurement error, thus affecting the accuracy and precision of currently established epidemiological associations between alcohol itself, alcoholic beverage consumption, and health or disease. Therefore, a more objective assessment of alcohol intake would be very valuable, which may be established through biomarkers of food intake (BFIs). Several direct and indirect alcohol intake biomarkers have been proposed in forensic and clinical contexts to assess recent or longer-term intakes. Protocols for performing systematic reviews in this field, as well as for assessing the validity of candidate BFIs, have been developed within the Food Biomarker Alliance (FoodBAll) project. The aim of this systematic review is to list and validate biomarkers of ethanol intake per se excluding markers of abuse, but including biomarkers related to common categories of alcoholic beverages. Validation of the proposed candidate biomarker(s) for alcohol itself and for each alcoholic beverage was done according to the published guideline for biomarker reviews. In conclusion, common biomarkers of alcohol intake, e.g., as ethyl glucuronide, ethyl sulfate, fatty acid ethyl esters, and phosphatidyl ethanol, show considerable inter-individual response, especially at low to moderate intakes, and need further development and improved validation, while BFIs for beer and wine are highly promising and may help in more accurate intake assessments for these specific beverages.

Positive blood phosphatidylethanol concentration is associated with unfavorable waitlist-related outcomes for patients medically appropriate for liver transplantation

BACKGROUND

Excessive alcohol use is a leading etiology of liver disease and indication for liver transplantation. Accurate measurement of alcohol use remains a challenge in the management of patients in the pre-, peri-, and post-liver transplant settings. Blood 16:0-18:1 phosphatidylethanol (PEth) concentration is a sensitive and specific biomarker of binge and moderate, chronic alcohol use. As PEth has the longest detection window of available blood-based direct alcohol biomarkers for moderate to heavy drinking, it shows promise as an indicator of patterns and chronicity of drinking. However, the utility of PEth in clinical liver transplantation is understudied. This study examines the association of PEth results with liver transplantation waitlist-focused patient outcomes.

METHODS

Retrospective data for all patients tested for PEth for a one-year period at a tertiary care medical center with an active liver transplantation program were abstracted. Indications for PEth testing, liver transplantation waitlist-related outcomes (e.g., listing and delisting) following testing and associations of PEth results with other parameters were analyzed.

RESULTS

Over a one-year period, 153 PEth tests were performed on 109 individuals. The most frequent indications for PEth testing were as an objective indicator of alcohol use patterns (86.3%) and to assess alcohol as a putative etiology of liver injury (13.7%). Of the 109 patients, 56 were medically appropriate for liver transplantation. Medically acceptable candidates with unfavorable transplantation waitlist-related outcomes (delisting, deferment of transplant evaluation, deferment of listing until completion of recommended alcohol rehabilitation, and being deemed not a transplant candidate) were at least 3.41 times more likely to have a positive PEth test than those with favorable transplantation waitlist-related outcomes (odds ratio 3.41, confidence interval 3.41 to ∞, p = 0.001).

CONCLUSION

This single-center study reporting a comprehensive account of PEth utilization at a liver transplant center demonstrates that liver transplantation waitlist-related outcomes are associated with PEth test results. Patients with positive PEth tests were more likely to have unfavorable transplant waitlist-related outcomes. PEth testing has not been validated as a predictor of relapse to drinking in post-transplant patients and because its utility in the pre-transplant setting is unclear its use could lead to disparities in the selection of patients for liver transplantation.

Determination of Ethyl Glucuronide and Ethyl Sulfate in Human Whole Blood and Vitreous Humor by LC-MS-MS and Applications to the Interpretation of Postmortem Ethanol Findings

Identifying the source of ethanol in a decedent remained a complicated problem for forensic toxicologists because of postmortem ethanol formation. As ethanol's non-oxidative metabolites, ethyl glucuronide (EtG) and ethyl sulfate (EtS) have the potential to distinguish between antemortem ethanol consumption and postmortem ethanol formation, due to their high sensitivity and selectivity. In the current study, a simple and quick liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed for the determination of EtG and EtS in human whole blood and vitreous humor (VH). A total of 20 μL of the sample was precipitated by methanol, and the analytes were detected by LC-MS/MS in a run of 6 min. This method achieved high sensitivity (limits of detection: 2 ng/mL for both EtG and EtS), with linearity in the range of 5-10,000 ng/mL in both whole blood and VH. Deviations in accuracy, inter- and intra-day precision were all lower than 15% at three quality control levels. Subsequently, this method was applied to 62 real forensic cases. Only blood samples were available in 52 cases. Paired blood and VH samples were present in 10 cases. The concentrations of EtG and EtS in blood were in the range of 0-22,264.8 ng/mL and 0-2,126.0 ng/mL, respectively. In one case with both blood and VH, the blood ethanol concentration was 1.22 mg/mL, with EtG and EtS both below limits of quantification (5 ng/mL) in VH, and no EtG and EtS found in whole blood. The results suggested that EtG and EtS were useful markers for the interpretation of ethanol resource in postmortem blood and VH.

A novel fast-dried urine spot-based method for the analysis of EtS and EtG in urine by liquid chromatography tandem mass spectrometry

Ethyl sulfate (EtS) and ethyl glucuronide (EtG) in urine are biomarkers to monitor ethanol consumption. Due to their high polarity, severe matrix effects have been observed during analysis of EtS and EtG in urine by liquid chromatography tandem mass spectrometry (LC-MS/MS), which can lead to a loss of sensitivity and accuracy. In the present study, a novel and simple sample preparation approach based on fast-dried urine spot was established to reduce the matrix effect of EtS and EtG in urine. 20 μL of urine was dropped on the Whatman 903# paper and was subsequently dried by microwave in one minute. After ultrasonic assisted extraction with 500 μL of methanol, the analysis was conducted using an LC-MS/MS system. Limits of detection were 5 ng/mL and linear ranges were 10 ng/mL-10 μg/mL for both EtS and EtG. Matrix effects were in the range of 99.3-107.8% for EtS and 86.7-91.0% for EtG at three QC levels. Matrix effects for EtS and EtG were compared between the current method and other sample preparation methods including protein precipitation, and solid-phase extraction. The results showed that this fast-dried urine spot-based extraction method could eliminate matrix effects significantly in analysis of urine EtS and EtG by LC-MS/MS.

Quantitative Determination of Ethyl Glucuronide and Ethyl Sulfate in Postmortem and Antemortem Whole Blood Using Phospholipid Removal 96-Well Plate and UHPLC-MS-MS

Postmortem ethanol formation is a well-known problem in forensic toxicology. Ethyl glucuronide (EtG) and ethyl sulfate (EtS) are ethanol metabolites that can be used to distinguish antemortem alcohol intake from postmortem formation of ethanol and in addition can be a helpful tool in assessment of the hip-flask defense. To an aliquot of 100 µL whole blood, internal standard (IS) and water was added before protein precipitation treatment (PPT) with ice-cold acetonitrile (ACN). The supernatants were filtered through a 96-well phospholipid removal plate, evaporated to dryness and reconstituted in 150 µL water/ACN/formic acid (FA). Identification of compounds was performed using multiple reaction monitoring (MRM) in negative mode. Gradient elution was performed on a C18 column with methanol (MeOH) and 0.1% FA. The run time was 4.5 min, and 0.5 µL was injected on an ultra-high-performance liquid chromatography–tandem mass spectrometry (UHPLC–MS-MS) instrument. Linearity was achieved (coefficient of determination (R²) ≥ 0.999) for EtG in the range of 0.089 to 22 mg/L (0.40–100 µM) and EtS 0.025 to 6.3 mg/L (0.20–50 µM). The limit of quantification (LOQ) was 0.067 mg/L (0.30 µM) for EtG and 0.019 mg/L (0.15 µM) for EtS. Between assay accuracy was –15% to 8% and precision reported as relative standard deviation (RSD) was ≤ 4.5%. Precision, estimated as the RSD of the concentration difference between results from two independent analyses of authentic whole blood samples, was ≤ 6.7%. Recovery was ≥ 61% for EtG and ≥ 77% for EtS and matrix effects (ME) were 99% to 103%. Method comparison was carried out with a previously used UHPLC–MS-MS method, and satisfactory agreement was achieved, and external proficiency testing control samples had z-score < ± 1. The method has been used in routine work for more than 4 years analyzing about 6,000 antemortem and postmortem whole blood samples and has proven to be robust and reliable.

Ethyl glucuronide hair testing: A review

Ethyl glucuronide (EtG) is a minor, non-oxidative ethanol metabolite that can be detected in several matrices (e.g. blood, urine, hair, meconium) for variable periods of time. Quantification of EtG in hair (hEtG) has established itself, over recent years, as one of the most reliable biomarkers of long-term alcohol consumption habits, with the Society of Hair Testing (SoHT) offering cut-off values for assessment of both abstinence and heavy drinking (>60 g/day). Despite its high diagnostic performance, however, issues concerning inter- and intra-laboratory variability as well as data interpretation are still being investigated and represent the ultimate barrier to widespread acceptance of hEtG in the forensic context. The aim of this review is to summarize currently available analytical methods of hEtG testing, provide a framework to understand current hEtG cut-offs and their possible upcoming changes (in particular, a lower abstinence cut-off has been proposed for the 2019 revision of the SoHT consensus), and offer a schematic but exhaustive overview of the pitfalls in result reproducibility and interpretation that may limit applications of hEtG testing in the forensic context. Ultimately, the purpose of the authors is not to undermine the reliability of hEtG as an alcohol use marker, but rather to enhance it by promoting familiarization with all aspects related to it, from ethanol pharmacokinetics and EtG incorporation into hair, to sample preparation and analytical methods, to specific cases warranting close attention and additional tests for correct interpretation of hEtG results.