Ethyl glucuronide in hair: Is it a reliable marker of chronic high levels of alcohol consumption?

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.

Does ethyl glucuronide in hair correlate with alcohol consumption? A comparative study with other traditional biomarkers among individuals with alcohol dependence syndrome

AIM

Ethyl glucuronide (EtG) in hair is a direct biomarker proven to be useful for the detection of chronic excessive alcohol use. This study investigated the association of self-reported alcohol consumption with traditional biomarkers: GGT, AST, ALT, CDT, and MCV in blood and a direct biomarker, hair EtG, in a total of 122 patients with alcohol dependence syndrome. The diagnostic accuracy of the biomarkers to differentiate heavy from non-heavy drinkers was also evaluated.

METHOD

GGT, AST, and ALT in serum were measured by Automated Chemistry Analyzer, MCV in blood was measured by Haematology Analyzer, serum CDT was analyzed by ELISA, and EtG in hair was evaluated by gas chromatography-mass spectrometry. The association between the biomarkers and the amount of alcohol consumed (self-reported) was determined using Spearman's rank correlation.

RESULTS

All participants showed EtG level above the cut-off (0.03 ng/mg). Hair EtG showed a statistically significant linear and positive correlation with the amounts (in grams) of alcohol consumed (r = 0.60; p < 0.001). No correlation was observed among the traditional biomarkers and the quantity of alcohol consumed. Also, EtG showed an excellent receiver operating characteristic (ROC) curve (98%) with good sensitivity (85%) and specificity (60%) to classify heavy drinkers among individuals with alcohol dependence syndrome.

CONCLUSION

Hair EtG can be helpful to estimate retrospective alcohol consumption in long-term chronic alcohol consumption cases. Hair EtG also provides a reliable diagnostic test to detect heavy drinkers among individuals with alcohol dependence syndrome.

Validation of hair ethyl glucuronide using transdermal monitoring and self-reported alcohol use in women of childbearing potential

Aim

The present study aimed to evaluate the validity of hair ethyl glucuronide concentrations compared with transdermal alcohol concentration and self‐reported alcohol use.

Methods

This trial included 25 adolescent and young adult females, aged 16‐24, who reported at least one heavy drinking episode (≥4 drinks) in the two weeks prior to baseline. All participants were asked to wear an alcohol biosensor over a one‐month prospective study. Detailed self‐report of drinking behaviors was assessed weekly. Estimates of blood alcohol concentration were computed from self‐report data using the National Highway and Transportation Safety Administration equation. Transdermal alcohol concentration and estimated blood alcohol concentration data were categorized into at‐risk (>0.05 g/dL alcohol) and high‐risk (>0.08 g/dL alcohol) drinking events. Hair ethyl glucuronide concentration, total number of drinking events, moderate (>0.05 g/dL) and high level (>0.08 g/dL) of transdermal alcohol concentration, and estimated blood alcohol concentration drinking events were analyzed with Spearman's rank correlation test for validity comparisons.

Results

No significant correlations were found between hair ethyl glucuronide values and total number, and moderate or high levels of detected drinking events by estimated blood alcohol concentration or transdermal alcohol concentration. Total number of drinking events detected and number of drinking events >0.08 g/dL using estimated blood alcohol concentration and transdermal alcohol concentration methods were significantly correlated with each other (respectively, R = .33, P < .05; R = .42, P < .05).

Conclusion

Our findings indicate that, due to the number of false negatives, hair ethyl glucuronide concentrations should be used with caution for monitoring abstinence from alcohol use.

Ethyl glucuronide, a marker of alcohol consumption, correlates with metabolic markers of oxidant stress but not with hemolysis in stored red blood cells from healthy blood donors

BACKGROUND

Red blood cell (RBC) storage in the blood bank is associated with the progressive accumulation of oxidant stress. While the mature erythrocyte is well equipped to cope with such stress, recreative habits like alcohol consumption may further exacerbate the basal level of oxidant stress and contribute to the progress of the storage lesion.

STUDY DESIGN AND METHODS

RBC levels of ethyl glucuronide, a marker of alcohol consumption, were measured via ultra-high-pressure liquid chromatography coupled with high-resolution mass spectrometry. Analyses were performed on 599 samples from the recalled donor population at Storage Days 10, 23, and 42 (n = 250), as part of the REDS-III RBC-Omics (Recipient Epidemiology Donor Evaluation Study III Red Blood Cell-Omics) study. This cohort consisted of the 5th and 95th percentile of donors with extreme hemolytic propensity out of the original cohort of 13,403 subjects enrolled in the REDS-III RBC Omics study. Ehtyl glucuronide levels were thus correlated to global metabolomics and lipidomics analyses and RBC hemolytic propensity.

RESULTS

Ethyl glucuronide levels were positively associated with oxidant stress markers, including glutathione consumption and turnover, methionine oxidation, S-adenosylhomocysteine accumulation, purine oxidation, and transamination markers. Decreases in glycolysis and energy metabolism, the pentose phosphate pathway and ascorbate system were observed in those subjects with the highest levels of ethyl glucuronide, though hemolysis values were comparable between groups.

CONCLUSION

Though preliminary, this study is suggestive that markers of alcohol consumption are associated with increases in oxidant stress and decreases in energy metabolism with no significant impact on hemolytic parameters in stored RBCs from healthy donor volunteers.

The influence of caffeine on ethyl glucuronide levels in rat serum and in rat hair

BACKGROUND

Ethanol and caffeine are the most widely used psychoactive substances in the world, with an observed steady increase in the combined consumption of alcohol and caffeine. Specific signs of ethanol-caffeine interactions have been reported both in humans and in animals. The metabolic effects of these interactions have not been fully elucidated. There are no published reports on the influence of caffeine on ethyl glucuronide (EtG) formation. EtG is a direct metabolite of ethanol and is very often used as a biomarker of alcohol consumption. Here, we investigated the influence of caffeine on the formation of EtG in rat plasma and EtG incorporation into the hair.

METHODS

Studies were conducted on three male Wistar rat groups, each receiving either ethanol at 3 g/kg/day, ethanol (at the same dose) with caffeine at 3 mg/kg/day, or caffeine at 3 mg/kg/day for four weeks. EtG and caffeine levels were evaluated in hair and in blood after the last administration.

RESULTS

Blood EtG levels after the administration of ethanol together with caffeine were significantly higher than after the administration of ethanol alone. EtG levels in rat hair in the ethanol-and-caffeine group were also higher than in the ethanol-only group, but the difference was not statistically significant.

CONCLUSION

This study shows the possible effect of ethanol and caffeine co-administration on EtG formation. Caffeine stimulates EtG synthesis resulting in increased blood and, possibly, hair levels of this metabolite. However, the role of these changes in estimating alcohol consumption requires further studies.

Alcohol Biomarkers in Clinical and Forensic Contexts

BACKGROUND

Biomarkers of alcohol consumption are important not only in forensic contexts, e.g., in child custody proceedings or as documentation of alcohol abstinence after temporary confiscation of a driver's license. They are increasingly being used in clinical medicine as well for verification of abstinence or to rule out the harmful use of alcohol.

METHODS

This review is based on pertinent publications that were retrieved by a selective literature search in PubMed concerning the direct and indirect alcohol markers discussed here, as well as on the authors' experience in laboratory analysis and clinical medicine.

RESULTS

Alongside the direct demonstration of ethanol, the available markers of alcohol consumption include the classic indirect markers carbohydrate-deficient transferrin (CDT), gamma-glutamyltransferase (GGT), and mean corpuscular volume (MCV) as well as direct alcohol markers such as ethyl glucuronide (EtG) and ethyl sulfate (EtS) in serum and urine and EtG and fatty acid ethyl esters (FAEE) in hair. Phosphatidylethanol (PEth) is a promising parameter that com - plements the existing spectrum of tests with high specificity (48-89%) and sensi - tivity (88-100%). In routine clinical practice, the demonstration of positive alcohol markers often leads patients to admit previously denied alcohol use. This makes it possible to motivate the patient to undergo treatment for alcoholism.

CONCLUSION

The available alcohol biomarkers vary in sensitivity and specificity with respect to the time period over which they indicate alcohol use and the minimum extent of alcohol use that they can detect. The appropriate marker or combination of markers should be chosen in each case according to the particular question that is to be answered by laboratory analysis.

Influence of Body Mass Index on Hair Ethyl Glucuronide Concentrations

AIM

Analysis of ethyl glucuronide (EtG) concentrations in hair is increasingly used to estimate the consumption of alcohol of the prior months. Linear correlations between the amount of alcohol consumed and the concentration of EtG in hair have been reported, and several variables that may influence this correlation have been investigated: e.g. cosmetic hair treatments, gender influences or hair color. Here, we investigate the influence of body mass index (BMI) on this correlation.

METHODS

A post hoc analysis on the influence of BMI on the relation between amounts of alcohol consumed and the measured EtG concentrations in hair in 199 participants.

RESULTS

Our data show higher EtG concentrations in participants with high BMI (≥25) compared to participants with low BMI (<25) (P = 0.001) across a wide range of amounts of alcohol consumed.

CONCLUSIONS

We conclude that BMI should be taken into account when interpreting hair EtG concentrations.

SHORT SUMMARY

Ethyl glucuronide concentrations in hair (hEtG) can be used to estimate the consumption of alcohol of the prior months. Body mass index (BMI) influences this relation and BMI should be taken into account when interpreting hEtG concentrations in participants with high BMI (≥25) compared to participants with low BMI (<25).

Effects of various sample pretreatment procedures on ethyl glucuronide quantification in hair samples: Comparison of positivity rates and appraisal of cut-off values

The quantification of ethylglucuronide (EtG) in hair is nowadays recognized as the approach with the highest diagnostic performance to evaluate harmful drinking. A widely accepted cut-off of 30pg/mg has been selected after several accurate compared studies. While most of the studies that were used to establish the appropriate cut-off value prescribed to cut hair into small segments before their extraction, hair milling has subsequently been identified as the most efficient pretreatment procedure and was therefore recommended in the last Consensus document issued by the Society of Hair Testing. In this study, we initially compared the results obtained with the two sample preparations, namely cutting and milling, both being applied to the same specimens (n=781). Among these, 205 samples produced measurable EtG values with both methods, with differences ranging from -41.7% up to +415% (the mean increase in EtG concentration, switching from cutting to milling, was +62.1% and the median was +42.3%). Among the aforementioned 205 samples, 29 specimens (3.7% of the total 781 samples) produced significantly different outcome, being classified as negative (i.e., below 30pg/mg) if the cutting procedure is used, but largely positive (above 40pg/mg) when milling is used. Subsequently, the positivity rates obtained on a large population dataset (>27,000 samples) with the two procedures, were retrospectively compared using variable cut-offs values. The percentage of head hair samples with EtG concentration exceeding 30pg/mg upon application of the milling procedure shows a 45% increase (from 10.9% to 15.8%) with respect to cutting procedure, whereas the fraction of hair samples with EtG exceeding 40pg/mg (10.5%) overlaps the percentage of positive samples obtained after cutting pretreatment and applying a cut-off of 30pg/mg. On the basis of these results, it would be worth considering the application of cut-off values linked with the pretreatment procedure, taking into account the results of forthcoming inter-laboratory calibrations.

Ethyl glucuronide concentrations in hair: a controlled alcohol-dosing study in healthy volunteers

Ethyl glucuronide (EtG) is a minor phase II metabolite of alcohol that accumulates in hair. It has been established as a sensitive marker to assess the retrospective consumption of alcohol over recent months using a cut-off of ≥7 pg/mg hair to assess repeated alcohol consumption. The primary aim was to assess whether amounts of alcohol consumed correlated with EtG concentrations in hair. Additionally, we investigated whether the current applied cut-off value of 7 pg/mg hair was adequate to assess the regular consumption of low-to-moderate amounts of alcohol. A prospective controlled alcohol-dosing study in 30 healthy individuals matched on age and gender. Individuals were instructed to drink no alcohol (N = 10), 100 g alcohol per week (N = 10) or 150 g alcohol per week (N = 10) for 12 consecutive weeks, before and after which hair was collected. Throughout the study, compliance to daily alcohol consumption was assessed by analyzing urine EtG three times weekly. Participants in the non-drinking group had median EtG concentrations of 0.5 pg/mg hair (interquartile range (IQR) 1.7 pg/mg; range < 0.21-4.5 pg/mg). Participants consuming 100 and 150 g alcohol per week showed median EtG concentrations of 5.6 pg/mg hair (IQR 4.7 pg/mg; range 2.0-9.8 pg/mg) and 11.3 pg/mg hair (IQR 5.0 pg/mg; range 7.7-38.9 pg/mg), respectively. Hair EtG concentrations between the three study groups differed significantly from one another (p < 0.001). Hair EtG concentrations can be used to differentiate between repeated (low-to-moderate) amounts of alcohol consumed over a long time period. For the assessment of repeated alcohol use, we propose that the current cut-off of 7 pg/mg could be re-evaluated.

Ethylglucuronide in maternal hair as a biomarker of prenatal alcohol exposure

While direct ethanol metabolites, including ethylglucuronide (EtG), play an important role for the confirmation of prenatal alcohol exposure (PAE), their utility is often limited by their short half-lives in blood and urine. Maternal hair allows for a retrospective measure of PAE for up to several months. This study examined the validity of hair EtG (hEtG) relative to self-reporting and five other biomarkers in 85 pregnant women. Patients were recruited from a UNM prenatal clinic, which provides care to women with substance abuse and addiction disorders. The composite index, which was based on self-reported measures of alcohol use and allowed us to classify subjects into PAE (n = 42) and control (n = 43) groups, was the criterion measure used to estimate the sensitivity and specificity of hEtG. Proximal segments of hair were collected at enrollment (average 22.0 gestational weeks) and analyzed by LC-MS/MS. At the same visit, maternal blood and urine specimens were collected for analysis of GGT, %dCDT, PEth, uEtG, and uEtS. The study population included mostly opioid-dependent (80%) patients, a large proportion of ethnic minorities (75.3% Hispanic/Latina, 8.2% American Indian, 4.7% African-American), and patients with low education (48.2% < high school). The mean maternal age at enrollment was 26.7 ± 4.8 years. Hair EtG demonstrated 19% sensitivity and 86% specificity. The sensitivities of other biomarkers were comparable (5-20%) to hEtG but specificities were higher (98-100%). Hair EtG sensitivity improved when combined with other biomarkers, especially with GGT (32.5%) and PEth (27.5%). In addition, validity of hEtG improved in patients with less frequent shampooing and those who did not use hair dyes/chemical treatments. These data suggest that hEtG alone is not a sufficiently sensitive or specific biomarker to be used separately for the identification of PAE, but might be useful in a battery along with other maternal biomarkers.

Examination of sex differences in fatty acid ethyl ester and ethyl glucuronide hair analysis

Clinical studies examining performance of fatty acid ethyl esters (FAEE) and ethyl glucuronide (EtG) in identifying excessive alcohol consumption have been primarily conducted in male populations. An impact of hair cosmetics in producing both false-negative EtG results and false-positive FAEE results has been demonstrated, suggesting a possible bias in female populations. This study evaluates FAEE-positive hair samples (>0.50 ng/mg) from n = 199 female and n = 73 male subjects for EtG. Higher FAEE/EtG concordance was observed amongst male over female subjects. Performance of multiple proposed EtG cut-off levels were assessed; amongst female samples, FAEE/EtG concordance was 36.2% (30 pg/mg), 36.7% (27 pg/mg), and 43.7% (20 pg/mg). Non-coloured hair demonstrated a two-fold increase in concordance (41.8 v. 20.8%) over coloured hair in the female cohort. FAEE levels did not differ between male and female subjects; however they were lower in coloured samples (p = 0.046). EtG was lower in female subjects (p = 0.019) and coloured samples (p = 0.026). A total of n = 111 female samples were discordant. Amongst discordant samples (EtG-negative), 26% had evidence of recent alcohol use including consultation histories (n = 20) and detectable cocaethylene (n = 9); 29% of discordant samples were coloured. False-negative risk with ethyl glucuronide analysis in females was mediated by cosmetic colouring. These findings suggest that combined analysis of FAEE and EtG is optimal when assessing a female population and an EtG cut-off of 20 pg/mg is warranted when using combined analysis. While concordant FAEE/EtG-positive findings constitute clear evidence, discordant FAEE/EtG findings should still be considered suggestive evidence of chronic excessive alcohol consumption.

Hair ethyl glucuronide as a biomarker of alcohol consumption in alcohol-dependent patients: role of gender differences

BACKGROUND

Ethyl glucuronide (EtG) is a minor alcohol metabolite that accumulates in hair and is proposed as a stable marker for the detection of chronic and excessive alcohol consumption above a cut-off level of 30pg/mg hair. A correlation between drinking behavior and EtG hair concentrations is observed, but large variability exists.

AIMS

To investigate the correlation between alcohol consumption and hair EtG concentrations in alcohol dependent patients, and the effect of gender differences as a factor for the variability on this correlation.

METHODS

EtG was measured by gas chromatography coupled to mass spectrometry in the hairs (first 3cm) of 36 alcohol dependent patients (25 males/11 females) starting and alcohol detoxification program. Factors that possibly influence EtG content in hair (except age and gender) were excluded. Detailed retrospective alcohol consumption was obtained over the last 3 months using the Timeline Follow Back interview.

RESULTS

Median total alcohol consumption over 3 months was 13,050g pure alcohol (range 60-650g/day). Hair EtG concentrations varied between 32 and 662pg/mg. There was a statistically significant linear and positive correlation between hair EtG and amounts of alcohol consumed (Pearson r=0.83; p<0.001), in both males (Pearson r=0.83; p<0.001) and females (Pearson r=0.76; p=0.007).

CONCLUSIONS

There is a linear correlation, with no significant effect of gender, between hair EtG concentrations and amounts of alcohol consumed in alcohol-dependent individuals. Analysis of EtG in hair can be applied to estimate retrospective alcohol consumption in both male and female alcohol dependent subjects using the same cut-off.

Global metabolic profiling for the study of alcohol-related disorders

Alcohol-related disorders are multifaceted since ethanol can induce profound metabolic perturbations when taken in excess. Global metabolic profiling strategies may aid the understanding of ethanol-related effects by shedding light on these metabolic changes and potentially revealing unknown mechanisms of ethanol toxicity. Here an overview of studies designed to explore the effects of alcohol (ethanol) consumption using holistic metabolite profiling approaches (metabonomics/metabolomics) is presented, demonstrating the potential of this methodology. The analytical technologies used (NMR, GC-MS and LC-MS), have been applied to the profiling of serum, plasma, urine and tissues, obtained from animal models or humans, after exposure to alcohol. From the metabolic profiling data of a range of biological samples, a number of endogenous metabolites have been proposed as potential ethanol consumption-related biomarkers. The biomarkers suggested by these studies, and the biochemical insights that they provide for understanding the effects of ethanol mechanisms of toxicity, are discussed.

Determination of ethyl glucuronide in hair improves evaluation of long-term alcohol abstention in liver transplant candidates

BACKGROUND & AIMS

Prior to listing patients for Orthotopic liver transplantation (OLT) an abstention period of 6 months is required. Ethyl glucuronide in the hair is a new reliable marker for the assessment of alcohol consumption. Here, the diagnostic value of determining the ethyl glucuronide concentration in the hair of liver transplant candidates was evaluated.

METHODS

In 63 transplant candidates with alcoholic liver cirrhosis and 25 control patients with cirrhosis of other aetiologies alcohol markers, i.e. hEtG, urine EtG, blood ethanol, methanol and carbohydrate deficient transferrin were determined in parallel to an interview with a psychologist.

RESULTS

A total of 19 (30%) transplant candidates admitted alcohol consumption within the last 6 months, while 39/63 (62%) were positive for at least one alcohol marker. In 52% of the 44 candidates denying alcohol consumption, abstention was disproved by detecting at least one positive alcohol marker, in 83% of cases by a positive hEtG result. In the control patients stating abstention from alcohol all hEtG tests were negative. No impact of renal or liver function on hEtG results was detected. A specificity of 98% and a positive predictive value of 92% were calculated for testing hEtG in proximal hair segment and applying a cut-off of 30 pg/mg.

CONCLUSIONS

In 52% of patients denying alcohol consumption within the last 6 months, alcohol abstention was disproved, in 83% of cases by hEtG testing. Therefore, hEtG is a promising new marker for the evaluation of long-term alcohol abstention in liver transplant candidates.

Ethyl glucuronide and ethyl sulfate

Alcohol misuse is associated with significant morbidity and mortality. Although clinical history, examination, and the use of self-report questionnaires may identify subjects with harmful patterns of alcohol use, denial or under-reporting of alcohol intake is common. Existing biomarkers for detecting alcohol misuse include measurement of blood or urine ethanol for acute alcohol consumption, and carbohydrate-deficient transferrin and gamma-glutamyl transferase for chronic alcohol misuse. There is a need for a biomarker that can detect excessive alcohol consumption in the timeframe between 1 day and several weeks. Ethyl glucuronide (EtG) is a direct metabolite of ethanol detectable in urine for up to 90 h and longer in hair. Because EtG has high specificity for excess alcohol intake, it has great potential for use in detecting "binge" drinking. Using urine or hair, this noninvasive marker has a role in a variety of clinical and forensic settings.

Hair ethyl glucuronide levels as a marker for alcohol use and abuse: a review of the current state of the art

BACKGROUND

Ethyl glucuronide (EtG) is a minor alcohol metabolite that has been proposed as a stable marker in hair to detect and quantify alcohol consumption over long time periods.

METHODS

We provide an outline of currently available techniques for EtG hair sample analysis and highlight the pitfalls related to data interpretation. The literature of EtG analysis has been reviewed from January 1980 up to August 2013. In addition, we present an overview of the clinical and forensic studies which have used EtG quantification in hair as a marker for alcohol consumption/abstinence and we provide suggestions for future research.

RESULTS

EtG is a stable marker in hair that can be used to detect and quantify alcohol consumption over long time periods. This alcohol metabolite remains in hair after complete elimination of alcohol. Currently, there are three main analytical techniques used to quantify EtG in hair: gas chromatography-mass spectrometry (GC-MS), gas chromatography-tandem mass spectrometry (GC-MS/MS), and liquid chromatography-tandem mass spectrometry (LC-MS/MS). No standardized protocols are yet available for the analysis of EtG levels in hair samples, and the current protocols vary in sample preparation and extraction procedures. Variables such as hair length, cosmetic treatment, gender, and pathophysiological conditions influence the final results and should be taken into account.

CONCLUSIONS

EtG quantification in hair is a useful tool for the objective detection of alcohol consumption over extended time periods, but care should be taken when interpreting the results.

Role of LC-MS/MS in hair testing for the determination of common drugs of abuse and other psychoactive drugs

Hair testing has been used in toxicological investigations for the last two decades, but only recently a remarkable extension of hair analysis to a variety of application fields was observed, besides drug abuse recognition. The dramatic improvements of LC-MS/MS instrumentation make the detection of tiny amounts of almost whatever drug in hair possible, even after single-dose intake. The progresses observed during the last 5 years in the detection of psychoactive substances in hair are reviewed herein. The literature is partitioned according to the target compounds, namely traditional drugs of abuse, new psychoactive substances and pharmaceutical psychoactive substances. The LC-MS/MS methods presented are addressed to determine a single class of drugs, with the primary aim of accurate quantitation, or to perform multiclass analysis, for rapid and effective screening protocols.

Determination of ethyl glucuronide levels in hair for the assessment of alcohol abstinence

This study examined the potential of a highly sensitive LC-MS/MS method for the determination of EtG in head hair (i) to ascertain alcohol abstinence, (ii) to estimate the basal level of EtG (sub-ppb concentrations) in head hair in a population of alcohol abstainers and (iii) to suggest a revision of cut-off values for assessing alcohol abstinence. An UHPLC-MS/MS protocol previously developed was modified and validated again to detect low EtG levels in head hair samples from a population of 44 certain abstainers and teetotalers. Basal level of EtG in hair was determined by a standard addition quantification method. The validated UHPLC-MS/MS method allowed detecting and quantifying 0.5 and 1.0 pg/mg of EtG in hair, respectively. EtG concentrations lower than 1.0 pg/mg were determined for 95% of abstainers; 30% of them had non-detectable (<0.5 pg/mg) EtG values. Two samples evidenced EtG concentrations higher than 1.0 pg/mg that were subsequently explained by unintentional ethanol exposure. The method's feature of high analytical sensitivity makes it particularly suitable for alcohol abstinence ascertainment and, in the same time, allows to tentatively estimate basal EtG concentrations in hair around 0.8±0.4 pg/mg. This finding opens a discussion on the possible origin of basal EtG concentration and potential sources of bias in the evaluation of alcohol abstinence. Cut-off value in the range of 1.0-2.0 pg/mg can be reliably proposed to support alcohol abstinence.

Application of mass spectrometry to hair analysis for forensic toxicological investigations

The increasing role of hair analysis in forensic toxicological investigations principally owes to recent improvements of mass spectrometric instrumentation. Research achievements during the last 6 years in this distinctive application area of analytical toxicology are reviewed. The earlier state of the art of hair analysis was comprehensively covered by a dedicated book (Kintz, 2007a. Analytical and practical aspects of drug testing in hair. Boca Raton: CRC Press and Taylor & Francis, 382 p) that represents key reference of the present overview. Whereas the traditional organization of analytical methods in forensic toxicology divided target substances into quite homogeneous groups of drugs, with similar structures and chemical properties, the current approach often takes advantage of the rapid expansion of multiclass and multiresidue analytical procedures; the latter is made possible by the fast operation and extreme sensitivity of modern mass spectrometers. This change in the strategy of toxicological analysis is reflected in the presentation of the recent literature material, which is mostly based on a fit-for-purpose logic. Thus, general screening of unknown substances is applied in diverse forensic contexts than drugs of abuse testing, and different instrumentation (triple quadrupoles, time-of-flight analyzers, linear and orbital traps) is utilized to optimally cope with the scope. Other key issues of modern toxicology, such as cost reduction and high sample throughput, are discussed with reference to procedural and instrumental alternatives.

Hair ethyl glucuronide is highly sensitive and specific for detecting moderate-to-heavy drinking in patients with liver disease

AIMS

Hair ethyl glucuronide (EtG) is a promising biomarker of moderate-to-heavy alcohol consumption and may have utility in detecting and monitoring alcohol use in clinical populations where alcohol use is of particular importance. This study evaluated the relationship between hair EtG and drinking in patients with liver disease.

METHODS

The subjects (n = 200) were patients with liver disease who presented for care at a university medical center. Alcohol use during the 3 months preceding participation in the study was assessed, and a sample of hair was obtained for EtG testing. Classification of drinking status (any drinking or averaging at least 28 g per day) by hair EtG was evaluated, as well as the effects of liver disease severity and demographic and hair care factors.

RESULTS

The area under the receiver operating characteristic curve for detecting an average of 28 g or more per day during the prior 90 days was 0.93. The corresponding sensitivity and specificity of hair EtG ≥8 pg/mg for averaging at least 28 g of ethanol per day were 92 and 87%, respectively. Cirrhosis and gender may have a modest influence on the relationship between drinking and hair EtG.

CONCLUSION

Hair EtG was highly accurate in differentiating subjects with liver disease averaging at least 28 g of ethanol per day from abstainers and lighter drinkers.

Higher levels of hair ethyl glucuronide in patients with decreased kidney function

BACKGROUND

Hair levels of ethyl glucuronide (EtG) are often used to differentiate social drinking from heavy drinking. Patients with decreased kidney function have delayed excretion of EtG, and increased incorporation into hair could be suspected. The aim of this study was to compare hair EtG levels in patients with decreased kidney function to those seen in healthy volunteers.

METHODS

Twelve patients with renal disease were included. The levels of EtG in hair were adjusted to estimated daily intake of ethanol (EDI) and compared to 21 previously published healthy individuals.

RESULTS

The levels of hair EtG in the 12 patients ranged between < limit of detection and 134 pg/mg, and the EDI ranged between 0.1 and 12 g. The levels of EtG in hair were significantly higher in the patients compared to healthy volunteers (p = 0.009).

CONCLUSIONS

These preliminary results indicate that hair levels of EtG in a population of patients with decreased kidney function should be interpreted with caution.

Comparison of ethyl glucuronide in hair with self-reported alcohol consumption

AIMS

Ethyl glucuronide (EtG) in hair is a proposed biomarker for alcohol consumption. This study compares hair EtG concentrations with self-reported alcohol consumption data, in individuals with a range of alcohol use.

METHODS

Hair was collected from 100 participants with a range of alcohol use. Participants completed an Alcohol Use Disorders Identification Test C questionnaire to record alcohol consumption. Participants were categorized into one of the four groups: tee-totallers (consuming 0 units a week), lower-risk drinkers (1-21 units a week), increasing-risk drinkers' consuming (22-50 units a week) and high-risk drinkers (over 50 units a week). Hair from the proximal 3 cm was analysed for EtG using gas chromatography-mass spectrometry/mass spectrometry.

RESULTS

EtG was detected in 29 out of 100 hair samples. Based on the Society of Hair Testing (SOHT) threshold of 30 pg/mg EtG, the hair test identified alcohol consumption in 57.9% of high-risk drinkers, 45.5% of increasing-risk drinkers and only 9.8% of lower-risk drinkers. EtG sensitivity was highest for high-risk drinkers (consuming more than 50 units a week), identified to be 0.52 using a 30 pg/mg threshold and 0.58 using a 45 pg/mg threshold. A positive result is highly likely to indicate any drinking (positive predictive value, 1.00). A negative result does not provide good evidence for abstinence (negative predictive value, 0.23).

CONCLUSIONS

EtG has been identified to be a low sensitivity marker that cannot be used quantitatively to determine alcohol exposure. EtG can be used qualitatively to indicate alcohol consumption with a positive result providing strong evidence for an individual drinking within the past 3 months.

Chronic excessive alcohol consumption diagnosis: comparison between traditional biomarkers and ethyl glucuronide in hair, a study on a real population

BACKGROUND

The study aimed to evaluate the diagnostic sensitivity (SE) and specificity (SP) of chronic alcohol misuse diagnosis by comparing traditional biomarkers with ethyl glucuronide (EtG), an ethanol direct metabolite, detected in the keratinic matrix.

METHODS

Seventy-six subjects tested for chronic alcohol abuse for different purposes were recruited. EtG was detected in hair, whereas the analyses of carbohydrate-deficient transferrin (CDT), alanine transaminase, aspartate transaminase, gamma-glutamyl transferase, mean corpuscular volume, and mean corpuscular hemoglobin were performed in serum samples.

RESULTS

Of the 76 patients examined, 26 were judged by the medical doctors as subjects with alcohol abuse problems and, therefore, not eligible for driving license renewal or liver transplant. EtG in hair (SE = 0.68, SP = 1.00) showed the best diagnostic SE and SP compared with the other biomarkers investigated. Among the traditional biomarkers, only CDT proved to be suitable for forensic purposes because of the high diagnostic specificity (SP = 1.00) although it showed poor diagnostic SE (0.27). The percentage of positive samples decreased for all the biomarkers by excluding the subjects with hepatic diseases, except for EtG and CDT, suggesting that these 2 biomarkers could be less affected by false positive results, because of hepatic diseases.

CONCLUSIONS

This study showed that when EtG in hair and CDT results are combined, diagnostic SE in chronic alcohol abuse diagnosis clearly improved, suggesting that complementary analysis of both these biomarkers provides the best diagnostic tool in suspected cases of chronic excessive alcohol consumption.

Liquid Chromatography-Tandem Mass Spectrometry Assay to Detect Ethyl Glucuronide in Human Fingernail: Comparison to Hair and Gender Differences

Over the past decade, the use of hair specimens for the long-term detection of the alcohol biomarker ethyl glucuronide has been increasing in popularity and usage. We evaluated the usefulness of fingernail clippings as a suitable alternative to hair for ethyl glucuronide detection. A liquid chromatography-tandem mass spectrometry method for the detection of ethyl glucuronide in fingernail clippings was fully validated and used to analyze the hair and/or fingernail specimens of 606 college-aged study participants. The limit of detection was 2 pg/mg, the limit of quantitation was 8 pg/mg and the method was linear from 8 to 2000 pg/mg. Intra- and inter-assay imprecision studies at three different concentrations (20, 40, 200 pg/mg) were all within 7.8% and all intra- and inter-assay bias studies at these levels were within 115.1% of target concentration. Ethyl glucuronide levels in fingernail (mean = 29.1 ± 55.6 pg/mg) were higher than ethyl glucuronide levels in hair (mean = 9.48 ± 22.3 pg/mg) and a correlation of the matched pairs was observed (r = 0.552, P < 0.01, n = 529). Evaluating each gender separately revealed that the correlation of male fingernail to male hair was large and significant (r = 0.782, P < 0.01, n = 195) while female hair to female fingernail was small yet significant (r = 0.249, P < 0.01, n = 334). The study results demonstrated that fingernail may be a suitable alternative to hair for ethyl glucuronide detection and may be the preferred sample type due to the lack of a gender bias.

Determination of ethyl glucuronide in nails by liquid chromatography tandem mass spectrometry as a potential new biomarker for chronic alcohol abuse and binge drinking behavior

A liquid chromatography tandem mass spectrometry method for ethyl glucuronide (EtG) detection and quantification in nails was developed and fully validated. Nails were extracted in 700 μL double-distilled water. EtG-d(5) was used as an internal standard. Reversed-phase separation was obtained with an isocratic mobile phase composed of 0.1% formic acid and acetonitrile (99:1) for 10 min. Quantification was performed by multiple reaction monitoring of two transitions per compound (EtG and internal standard). The assay was linear from 10 to 500 pg/mg. Validation parameters were studied at three different quality control levels (10, 50, and 300 pg/mg). Intraday, interday, and total imprecision had a coefficient of variation of less than 9.5%. Ion suppression and ion enhancement were negligible (less than 20%). No carryover was detected. The method was applied to several real cases, among teetotalers, social drinkers, and heavy drinkers. A questionnaire, together with the informed consent form, was given to all the participants in order to evaluate alcohol intake in the one month before sample collection. Nail EtG levels in a social drinker were much higher than the concentrations of EtG in hair provided by the same subject, thus suggesting potential high sensitivity in evaluating both chronic excessive alcohol consumption and binge drinking habits.

Ethyl glucuronide

Alcohol is associated with significant morbidity and mortality. Subjects abusing alcohol can be identified through clinical history, examination or self-report questionnaires. A range of biomarkers is available for detecting alcohol misuse, but there is still a need for a marker that can detect alcohol consumption in the time window between one day (ethanol) and one week (gamma-glutamyl transpeptidase and carbohydrate-deficient transferrin). Ethyl glucuronide is a direct metabolite that can be detected in urine for up to 90 h and has the potential to become a useful marker of 'binge' drinking. As a non-invasive marker, it could have a role in a variety of clinical and forensic settings.