Ethyl glucuronide-a biological marker for recent alcohol consumption

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

Ethyl glucuronide (EtG) and ethyl sulphate (EtS) are 2 non-oxidative and direct metabolites of ethanol. EtG is known to accumulate in hair and has proved to be a reliable biomarker for detection of chronic alcohol consumption. EtS has been analysed in blood and urine but has never been reported in hair. This article presents the first analytical assay based on liquid chromatography coupled to tandem mass spectrometry for the quantification of EtS in hair. Sample preparation, chromatographic, and mass spectrometric parameters, such as solid-phase extraction, column type, and transitions were optimised. The method was validated according to the guidelines of the European Medicine Agency, fulfilling the requirements for limit of quantification (LOQ), linearity, accuracy, precision, carry-over, matrix effects, and recovery. Linearity ranged from 5 to 500 pg mg^-1 and the LOQ was achieved at 5 pg mg^-1 . The novel method was successfully applied to hair samples (n = 40) from patients treated for alcohol use disorders. EtS concentrations in hair ranged from 24 to 1776 pg mg^-1 , while EtG concentrations in hair ranged from 1 to 1149 pg mg^-1 . Hair concentrations of EtS and EtG were compared to assess the relationship between both biomarkers. There was a significant and positive correlation between EtS and EtG in hair, suggesting that EtS can be used as a biomarker for alcohol consumption. Relatively high basal EtS levels were observed in alcohol-abstinent persons, comparable to what has been reported for EtG. The developed analytical procedure offers an alternative method to prove alcohol consumption using hair analysis.

Ethanol and ethyl glucuronide urine concentrations after ethanol-based hand antisepsis with and without permitted alcohol consumption

BACKGROUND

During hand antisepsis, health care workers (HCWs) are exposed to alcohol by dermal contact and by inhalation. Concerns have been raised that high alcohol absorptions may adversely affect HCWs, particularly certain vulnerable individuals such as pregnant women or individuals with genetic deficiencies of aldehyde dehydrogenase.

METHODS

We investigated the kinetics of HCWs' urinary concentrations of ethanol and its metabolite ethyl glucuronide (EtG) during clinical work with and without previous consumption of alcoholic beverages by HCWs.

RESULTS

The median ethanol concentration was 0.7 mg/L (interquartile range [IQR], 0.5-1.9 mg/L; maximum, 9.2 mg/L) during abstinence and 12.2 mg/L (IQR, 1.5-139.6 mg/L; maximum, 1,020.1 mg/L) during alcohol consumption. During abstinence, EtG reached concentrations of up to 958 ng/mL. When alcohol consumption was permitted, the median EtG concentration of all samples was 2,593 ng/mL (IQR, 890.8-3,576 ng/mL; maximum, 5,043 ng/mL). Although alcohol consumption was strongly correlated with both EtG and ethanol in urine, no significant correlation for the frequency of alcoholic hand antisepsis was observed in the linear mixed models.

CONCLUSIONS

The use of ethanol-based handrub induces measurable ethanol and EtG concentrations in urine. Compared with consumption of alcoholic beverages or use of consumer products containing ethanol, the amount of ethanol absorption resulting from handrub applications is negligible. In practice, there is no evidence of any harmful effect of using ethanol-based handrubs as much as it is clinically necessary.

Pharmacokinetic and pharmacodynamic drug interactions with ethanol (alcohol)

Ethanol (alcohol) is one of the most widely used legal drugs in the world. Ethanol is metabolized by alcohol dehydrogenase (ADH) and the cytochrome P450 (CYP) 2E1 drug-metabolizing enzyme that is also responsible for the biotransformation of xenobiotics and fatty acids. Drugs that inhibit ADH or CYP2E1 are the most likely theoretical compounds that would lead to a clinically significant pharmacokinetic interaction with ethanol, which include only a limited number of drugs. Acute ethanol primarily alters the pharmacokinetics of other drugs by changing the rate and extent of absorption, with more limited effects on clearance. Both acute and chronic ethanol use can cause transient changes to many physiologic responses in different organ systems such as hypotension and impairment of motor and cognitive functions, resulting in both pharmacokinetic and pharmacodynamic interactions. Evaluating drug interactions with long-term use of ethanol is uniquely challenging. Specifically, it is difficult to distinguish between the effects of long-term ethanol use on liver pathology and chronic malnutrition. Ethanol-induced liver disease results in decreased activity of hepatic metabolic enzymes and changes in protein binding. Clinical studies that include patients with chronic alcohol use may be evaluating the effects of mild cirrhosis on liver metabolism, and not just ethanol itself. The definition of chronic alcohol use is very inconsistent, which greatly affects the quality of the data and clinical application of the results. Our study of the literature has shown that a significantly higher volume of clinical studies have focused on the pharmacokinetic interactions of ethanol and other drugs. The data on pharmacodynamic interactions are more limited and future research addressing pharmacodynamic interactions with ethanol, especially regarding the non-central nervous system effects, is much needed.

The influence of cleansing shampoos on ethyl glucuronide concentration in hair analyzed with an optimized and validated LC-MS/MS method

Ethyl glucuronide (EtG) is widely used as a marker for assessment of alcohol consumption behavior. In this study the influence of special cleansing shampoos on ethyl glucuronide concentrations in hair was investigated. For that purpose an optimized LC-MS/MS method was developed using a Hypercarb™ porous graphitic carbon (PGC) column and validated according to the guidelines of the German Society of Toxicological and Forensic Chemistry (GTFCh). Twenty-five hair samples of persons with known alcohol consumption behavior were investigated (21 positive samples and 4 blank samples). The hair samples were divided into two strands of hair and were analyzed after treatment with one out of four cleansing shampoos and without shampoo treatment. EtG concentrations in hair did not show any significant differences after a single application of the different cleansing shampoos. EtG was still detectable in all the positive hair samples without significant concentration change. These results clearly demonstrated that a single application of the tested cleansing shampoos did not remove EtG from hair and therefore had no influence on EtG concentration in analytical hair analysis.

Alcohol metabolism

This article describes the pathways and factors that modulate blood alcohol levels and metabolism and describes how the body disposes of alcohol. The various factors that play a role in the distribution of alcohol in the body, influence the absorption of alcohol, and contribute to first-pass metabolism of alcohol are described. Most alcohol is oxidized in the liver, and general principles and overall mechanisms for alcohol oxidation are summarized. The kinetics of alcohol elimination in-vivo and the various genetic and environmental factors that can modify the rate of alcohol metabolism are discussed.

A high-performance liquid chromatographic-tandem mass spectrometric method for the determination of ethyl glucuronide and ethyl sulfate in urine validated according to forensic guidelines

Ethyl glucuronide (EtG) and ethyl sulfate (EtS) are powerful markers for alcohol intake and abuse. Several analytical procedures for the quantification of EtG and EtG in serum and urine have been developed so far. Many of the published methods show limits of detections (LODs) or limits of quantifications (LOQs) for EtG in urine within the range of 0.1 mg/L or higher. Since this is the actual cutoff value for proving abstinence in Germany, problems may occur if urine samples are highly diluted. In this paper, the validation of a highly sensitive, fast and simple LC-MS-MS for the determination of EtG and EtS in urine is described. The calibration curves for EtG and EtS is linear over the whole range (0.025-2.0 mg/L). Very low detection limits can be achieved (LOD: EtG 0.005 mg/L, EtS 0.005 mg/L; and LOQ: EtG 0.019 mg/L, EtS 0.015 mg/L). All data for selectivity, precision and accuracy, recovery, as well as for the processed sample and the freeze/thaw stability, comply with the guidelines of the German Society of Toxicological and Forensic Chemistry. Strong matrix-related effects can be compensated for by using an internal standard. Finally, the applicability of the procedure is proven by analysis of 87 human urine samples and by successful participation in interlaboratory comparison tests.

Inhibition of bacterial degradation of EtG by collection as dried urine spots (DUS)

Ethyl glucuronide (EtG) and ethyl sulfate (EtS) are direct alcohol consumption markers widely used nowadays for clinical and forensic applications. They are detectable in blood and urine even after consumption of trace amounts of ethanol and for a longer time frame, being detectable even when no more ethanol is present. The instability of EtG against bacterial degradation in contaminated urine samples and/or the possible postcollection synthesis of this metabolite in samples containing, e.g., Escherichia coli and ethanol, may cause false identification of alcohol uptake. Therefore, it is of paramount importance to constrict these error sources by inhibition of any bacterial growth causing hydrolization or synthesis of EtG. This study evaluates a new method of collecting urine samples on filter paper, dried urine spots (DUS), for simultaneous detection of EtG, EtS and creatinine, having the great advantage of inhibiting bacterial activity. In addition, a method validation for the determination of EtG and EtS in DUS was performed according to the FDA guidelines. Sterile-filtered urine was spiked with EtG and EtS, inoculated with E. coli and incubated. Liquid and dried urine samples were collected after various time intervals up to 96 h. Liquid samples were frozen immediately after collection, whereas aliquots for DUS were pipetted onto filter paper, allowed to dry and stored at RT until analysis 1 week after. The specimens were analyzed by LC-ESI-MS/MS. As expected, degradation of EtG, but not of EtS, was observed in contaminated liquid urine samples. However, the specimens collected on filter paper and stored at RT showed no degradation during storage. Therefore, collecting urine samples on filter paper for EtG and EtS analysis turns out to be a reliable method to avoid bacterial degradation of EtG and EtS, and consequently, stabilization of these ethanol metabolites is achieved. In addition, simultaneous measurement of creatinine content as an indicator of urine dilution helps to interpret the results. Method validation for EtG and EtS in DUS was satisfactory, showing the linearity of the calibration curves in the studied concentration range, good precision, accuracy and selectivity.

Assessment of alcohol consumption among hepatitis C-positive people receiving opioid maintenance treatment using direct ethanol metabolites and self-report: a pilot study

This study was conducted to identify the alcohol consumption among hepatitis C-positive people receiving opioid maintenance therapy using self-report and biomarkers. A total of 49 people (28 male, 21 female) were hepatitis C virus (HCV) positive and were included. The alcohol use disorder identification test (AUDIT) and self-reported ethanol intake in the last 28 days were assessed. In addition to gamma-glutamyl-transferase (GGT) and mean corpuscular volume (MCV), ethyl glucuronide (EtG) and ethyl sulphate (EtS) were determined in serum and urine (UEtG, UEtS, SEtG) using liquid chromatography/tandem mass-spectroscopy (LC/MS-MS) with deuterated internal standards. Abstinence from alcohol was reported for the last 28 days by 13 participants and for the last 7 days by 22. AUDIT was > 8 in 27 cases. The maximum values were 34.8 mg/l for UEtG, 5.3 mg/l for UEtS and 0.15 for SEtG. Among the 19 UEtG positives, 8 had not reported any ethanol intake in the 7 days prior to the study. Six participants reported intake of up to 320 g of ethanol in the last 7 days, but were negative for SEtG, UEtG and UEtS. Self-reported ethanol intake in the last 28 days correlated with AUDIT score (r = 0.733, P < 0.001), with the direct ethanol metabolites and MCV. In this population, abstinence and episodic heavy drinking are more common than in the general population. Episodic heavy drinking is a significant cause of acute risk in this population. Results from biomarker testing could indicate cases of under- as well as over-reporting of alcohol consumption. Further research on the diagnostic accuracy of direct ethanol metabolites, including the use of phosphatidylethanol (PEth), in this setting is needed.

Postcollection synthesis of ethyl glucuronide by bacteria in urine may cause false identification of alcohol consumption

BACKGROUND

Ethyl glucuronide (EtG) is a minor ethanol metabolite used as a specific marker to document recent alcohol consumption; confirm abstinence in treatment programs, workplaces, and schools; and provide legal proof of drinking. This study examined if bacterial pathogens in urine may enable postsampling synthesis of EtG and ethyl sulfate (EtS) from ethanol, leading to clinical false-positive results.

METHODS

Urine specimens with confirmed growth of Escherichia coli, Klebsiella pneumoniae, or Enterobacter cloacae were stored at room temperature in the presence of ethanol. Ethanol was either added to the samples or generated by inoculation with the fermenting yeast species Candida albicans and glucose as substrate. EtG and EtS were measured by LC-MS.

RESULTS

High concentrations of EtG (24-h range 0.5-17.6 mg/L) were produced during storage in 35% of E. coli-infected urines containing ethanol. In some specimens that were initially EtG positive because of recent alcohol consumption, EtG was also sensitive to degradation by bacterial hydrolysis. In contrast, EtS was completely stable under these conditions.

CONCLUSIONS

The presence of EtG in urine is not a unique indicator of recent drinking, but might originate from postcollection synthesis if specimens are infected with E. coli and contain ethanol. Given the associated risks for false identification of alcohol consumption and false-negative EtG results due to bacterial degradation, we recommend that measurement of EtG be combined with EtS, or in the future possibly replaced by EtS.

Ethyl sulphate: a direct ethanol metabolite reflecting recent alcohol consumption

BACKGROUND

Ethyl sulphate (EtS), a direct ethanol metabolite, appears to offer potential as a biomarker for recent alcohol consumption. Although its window of assessment is similar to that of ethyl glucuronide (EtG), there are differences between the two markers in their pathways for formation and degradation.

AIMS

(a) To assess the excretion of EtS compared to EtG and ethanol in drinking experiments with healthy volunteers, and (b) to elucidate the possibility of using the two metabolites for monitoring abstinence in substance use disorder patients during rehabilitation treatment.

DESIGN, SETTING, PARTICIPANTS

(a) Nine drinking experiments were performed by six healthy volunteers (two females, four males), with a mean age of 34.1 years (20-62), average oral intake of 0.2 g/kg ethanol (0.1-0.61), and having 74 spot urine samples. (b) Thirty-six substance abuse patients (mean age 41.9 years, 20-59; 22 males, 14 females) in a rehabilitation programme after withdrawal, producing 98 urine samples. Ethyl glucuronide and ethyl sulphate were measured using liquid chromatography tandem mass spectrometry (LC-MS/MS) using d5-EtG and d5-EtS, respectively, as an internal standard.

FINDINGS

(a)

VOLUNTEERS

EtG and EtS were detectable for up to 36 hours and reached the limits of determination in urine at 20.6 hours and 21.2 hours (median), respectively, after ethanol intake. EtG-100 (standardized to a creatinine of 100 mg/dl) reached its maximum level at 2.8 hours and EtS-100 at 2.1 hours (median) after the beginning of the experiment. Of the ethanol ingested, 0.022% was excreted as EtS in one volunteer. Eight samples were positive for EtS only and six for EtG only. Spearman's rank correlation coefficients of 0.84 (P < 0.0001) between EtG and EtS and 0.87 (P < 0.0001) between EtG-100 and EtS-100 were found. (b)

PATIENTS

of the 98 urine samples evaluated, 27 were positive for EtS and of these only 20 were also positive for EtG. Spearman's rank correlation coefficients of 0.84 (P < 0.0001) between EtG and EtS and 0.82 (P < 0.0001) between EtG-100 and EtS-100 were found.

CONCLUSIONS

The data from patients and volunteers suggest that the direct ethanol metabolite ethyl sulphate has the potential to serve as a biomarker of recent ethanol intake. Because EtG and EtS are formed via different pathways they might be used conjointly, thereby increasing sensitivity.

Urine as a Biological Specimen for Forensic Analysis of Alcohol and Variability in the Urine-to-Blood Relationship

This article concerns the use of urine as a biological specimen for determination of alcohol in clinical and forensic toxicology and discusses factors that might influence variability in the urine/blood concentration ratio of alcohol. A large number of human drinking experiments were conducted to determine the time course of urine-alcohol concentrations (UAC) in relation to blood-alcohol concentrations (BAC). The UAC and BAC curves were shifted in time and the BAC curve always began to decrease before the UAC started to decline. During the early absorption phase the UAC/BAC ratio was less than unity, whereas in the late absorption/distribution period the ratio was between 1.0-1.2. On reaching the post-absorptive phase, the UAC always exceeded BAC and UAC/BAC ratios averaged 1.3-1.4, increasing appreciably as BAC decreased towards zero. Alcohol-induced diuresis was most pronounced during the rising portion of the BAC curve and near to the peak value. After about 2 hours post-drinking, the production rate of urine diminished to the pre-drinking rate of about 0.5-1 mL/min. Drinking water during the post-absorptive phase of the alcohol curve produced dilute urine, as reflected in lower creatinine content and osmolality, although the concentration of ethanol remained unchanged. After subjects drank a moderate dose of ethanol (0.54-0.85 g/kg) about 2% of the dose was recoverable in the urine after 7 hours. Ethyl glucuronide, a minor metabolite of ethanol, was measured in urine samples from drunk drivers. The UAC/BAC ratio of ethanol in drunk drivers did not depend on the creatinine content of the urine and therefore the relative dilution of the specimens. When alcohol-free urine was spiked with glucose and infected with the yeast species Candida albicans, ethanol was produced by fermentation after approximately 24 hours storage at room temperature. This post-sampling synthesis of ethanol was prevented by sodium fluoride (1% weight by volume) in the urine tubes or by keeping the specimens in the cold (4 degrees C). The UAC and BAC were highly correlated (r > 0.95) in drunk drivers and in autopsy cases, although the residual standard deviations were appreciable. This speaks against attempting to estimate BAC indirectly from UAC in any individual case. The UAC/BAC ratio and the change in UAC between two successive voids can help to resolve whether a large amount of alcohol had recently been consumed. This information is useful to support or challenge allegations of drinking alcohol after driving, which has become known as the hip-flask defence.

Biological markers in alcoholism

Alcohol biomarkers include tests indicative of acute or chronic alcohol consumption (state markers), and markers of a genetic predisposition to develop alcohol dependence after chronic exposure (trait markers). While a comprehensive trait marker for alcohol dependence has not been identified, a number of successful state markers for monitoring drinking status are used clinically. These tests provide direct or indirect ways to estimate the amounts of alcohol consumed and the duration of ingestion, and to detect any harmful effects on body functions resulting from long-term misuse. The most obvious method to prove recent drinking is by demonstrating the presence of ethanol in body fluids or breath, but, because ethanol is cleared fairly rapidly from the body, this method is limited to detect only very recent drinking. Measurement of urinary 5-hydroxytryptophol or ethyl glucuronide provide more sensitive methods to disclose recent drinking, because their washout constants are much longer than for ethanol. The liver functions test (GGT, AST and ALT in serum) and the mean corpuscular volume of erythrocytes (MCV) are among the standard diagnostic tools used to identify chronic alcohol exposure. The main disadvantage with these measures is that they have low sensitivity for recent excessive intake, and that raised levels may result from several causes besides heavy drinking, implying a low specificity for alcohol. Carbohydrate-deficient transferrin (CDT), which refers to changes in the carbohydrate composition of serum transferrin, is a more specific marker for identifying excessive alcohol consumption and monitoring abstinence during outpatient treatment. The alcohol biomarkers improves knowledge of drinking patterns in both individuals and populations, and they are also valuable tools for the objective evaluation of treatment efforts. Alcohol markers have, for example, found uses in early identification of at-risk and harmful drinking, and they help to monitor abstinence and relapse in response to outpatient treatment.

Ethyl glucuronide--the direct ethanol metabolite on the threshold from science to routine use

AIMS

Current biological state markers remain suboptimal with regard to sensitivity and specificity for monitoring recent alcohol consumption in various settings. Furthermore, these biomarkers can be influenced by age, gender and a variety of substances and non-alcohol-associated diseases and do not cover fully the time axis for alcohol intake. Ethyl glucuronide (EtG) is a non-volatile, water-soluble, stable, direct metabolite of ethanol that can be detected in various body fluids, tissues and hair. Shortly after the consumption even of small amounts of ethanol, EtG becomes positive. It can detect ethanol intake up to 80 hours after the complete elimination of alcohol from the body, covering a unique and important time spectrum for recent alcohol use. EtG seems to meet the need for a sensitive and specific marker to elucidate alcohol use not detected by standard testing.

DESIGN, SETTING, PARTICIPANTS, METHODS AND FINDINGS

The literature was reviewed with a focus on possible diagnostic and therapeutic applications, currently available methods and future perspectives. To date, more than 4000 samples of body fluids, tissues and hair from approximately 1500 individuals have been assessed.

CONCLUSIONS

The data suggest that EtG is a useful tool in numerous settings, including alcohol and drug treatment (to detect lapse/relapse and for motivational feedback), in safety sensitive work settings where use is dangerous or in other settings where alcohol use may be risky (e.g. such as driving, work-place, pregnancy or monitoring physicians or other professionals who are in recovery and working) or for resolving forensic questions. If the question of recent alcohol consumption has to be answered in a binary way (yes/no), such as for determining lapses. the use of EtG in urine is among the preferred tests. The use of this marker alone and complementary with other biological state markers and self-reports is expected to lead to significant improvement in treatment outcome, therapy efficacy and cost reduction.

Ethyl glucuronide concentrations in two successive urinary voids from drinking drivers: relationship to creatinine content and blood and urine ethanol concentrations

The concentrations of alcohol in blood (BAC) and two successive urine voids (UAC) from 100 drunk drivers were compared with the concentration of ethyl glucuronide (EtG), a minor metabolite of ethanol in urine, and the urinary creatinine content as an indicator of dilution. The subjects consisted of 87 men with mean age 42.2+/-14.2 years (+/-standard deviation, S.D.) and 13 women with mean age 42.5+/-14.4 years. Ethanol was measured in blood and urine by headspace gas chromatography (GC) and EtG was determined in urine by liquid chromatography-mass spectrometry (LC-MS). The mean UAC was 2.53+/-1.15g/l for first void compared with 2.35+/-1.17g/l for second void, decreasing by 0.18+/-0.24g/l on average (P<0.001 in paired t-test). The ratios of UAC/BAC were 1.35+/-0.25 for first void and 1.20+/-0.16 for second void and the difference of 0.15+/-0.27 was statistically significant (P<0.001). The UAC/BAC ratio was not correlated with creatinine content of the urine specimens, whereas the concentration of urinary EtG was positively correlated with creatinine (r=0.64 for first void and r=0.62 for second void). The UAC was not correlated with urinary EtG directly (r=-0.03 for first void and r=0.08 for second void) but after adjusting for the relative dilution of the specimens (EtG/creatinine ratio) statistically significant positive correlations were obtained (r=0.58 for first void and r=0.57 for second void). The dilution of the urine, as reflected in creatinine content, is important to consider when EtG measurements are interpreted. The excretion of EtG in urine, like glucuronide conjugates of other drugs, is influenced by diuresis. EtG represents a sensitive and specific marker of acute alcohol ingestion with applications in clinical and forensic medicine.

Ethyl glucuronide discloses recent covert alcohol use not detected by standard testing in forensic psychiatric inpatients

BACKGROUND

Considerable lives and money could be saved if one could detect early stages of lapsing/relapsing behavior in addicted persons (e.g., in safety-sensitive workplaces) and could disclose harmful drinking in social drinkers. Due to the serious public health problem of alcohol use and abuse worldwide, markers of alcohol use have been sought. Both ethyl glucuronide (EtG) and phosphatidyl ethanol (PEth) appear to have high sensitivity and specificity and a time frame of detection that may elucidate alcohol use not detected by standard testing. Our aim was to assess their potential for detecting recent covert alcohol use under controlled conditions.

METHODS

Thirty-five forensic psychiatric inpatients in a closed ward who had committed a substance-related offense ( section sign 64 StGB), were followed for 12 months. The complete time spectrum of possible alcohol consumption was covered by the complementary use of breath and urinary ethanol (hours), urinary EtG (days), %carbohydrate-deficient transferrin (CDT)/PEth (weeks), and gamma-glutamyltranspeptidase (GGT)/mean corpuscular volume (MCV) (weeks-months).

RESULTS

Fourteen of the 146 urine samples examined were positive for EtG. In all EtG-positive cases, patients reported alcohol consumption of between 40 and 200 g of ethanol 12-60 hr prior to testing. Urinary and breath ethanol were positive in only one case. In the blood samples, PEth was not positive in any case and %CDT did not exceed the reference value. Isoelectric focusing showed no abnormal Tf subtypes.

CONCLUSIONS

The findings emphasize the diagnostic and therapeutic usefulness, specificity, and sensitivity of EtG as a marker of recent alcohol use. Such a test is needed in numerous settings, including alcohol and drug treatment (to detect lapse/relapse), in safety-sensitive work settings where use is dangerous or in other settings where use may be inappropriate (e.g., such as driving, workplace, pregnancy, or monitoring physicians or other professionals who are in recovery and working), or for testing other groups (such as children or those with medical problems) where alcohol use would be unhealthy or unsafe. The health, social and socioeconomic benefits arising from the future use of these markers is hard to overestimate.

Direct quantification of ethyl glucuronide in clinical urine samples by liquid chromatography-mass spectrometry

Ethyl glucuronide is a minor metabolite of ethanol, and its presence in urine can be used as a laboratory test to detect recent alcohol intake, even for some time after the ethanol is no longer measurable. A simple analytical procedure was developed based on direct injection of urine diluted with a deuterated internal standard into an electrospray liquid chromatographic-mass spectrometric (LC-MS) system. A novel LC system using a porous graphite column (Hypercarb) enabled an isocratic elution with retention times of 5-6 minutes. The intra- and inter-assay coefficients of variation were 2-12%, and the measuring range was 0.1-1,500 mg/L (0.45-6,750 micromol/L). Ethyl glucuronide was found to be stable in urine for more than 4 days at room temperature, and no artifactual formation was observed on storage of urine samples fortified with 1% ethanol. Ethyl glucuronide was not detected in urine samples collected after abstinence from alcohol. Intake of a very low amount (7 g) of ethanol produced ethyl glucuronide values up to 8.4 mg/L after 4 hours and was still detectable at 6 hours. When the method was applied for routine screening of 252 clinical urine samples (range, 0-1,240 mg/L), it fulfilled the need for a simple and reliable assay to be used in the evaluation of urinary ethyl glucuronide as a routine test of recent alcohol intake.

The ethanol conjugate ethyl glucuronide is a useful marker of recent alcohol consumption

BACKGROUND

Current biological state markers remain suboptimal with regard to sensitivity and specificity for monitoring alcohol consumption. The currently used state markers can be influenced by age, sex, and a variety of substances and non-alcohol-associated diseases and do not fully cover the time axis for alcohol intake. Ethyl glucuronide (EtG) is a promising, nonvolatile, water-soluble marker of recent alcohol consumption that is stable during storage and can be detected for an extended time period (up to 80 hr) after alcohol is completely eliminated from the body.

PATIENTS AND METHODS

In the WHO/ISBRA Study of State and Trait Markers of Alcohol Use and Dependence, EtG was determined in urine samples from 304 patients with an liquid chromotography, electrospray ionization double mass spectrometry (ESI-LC/MS-MS) method. Deuterium labeled EtG was used as internal standard. Determination limit was 0.1 mg/liter. All measurements were performed in duplicate. A calibration solution was measured after each 10 samples.

RESULTS

The following significant correlations were found for the Spearman rank correlation for the total sample between EtG and other variables: sobriety in days (r = -0.6), 5-hydroxytryptophol to 5-hydroxyindole-3-acetic acid (HTOL/HIAA) ratio (r = 0.58), ethanol level (r = 0.433), methanol level (r = 0.198), carbohydrate-deficient transferrin (r = 0.458), gamma-glutamyltransferase (r = 0.428), aspartate aminotransferase (r = 0.260), age (r = 0.264), and total grams of ethanol consumed in the previous month (r = 0.467). In a subsample of 277 subjects in whom no ethanol was detectable in urine, the following correlations with EtG levels were found: sobriety (days; r = -0.597), HTOL/HIAA ratio (r = 0.478), gamma-glutamyltransferase (r = 0.422), total grams of ethanol consumed last month (r = 0.395), and carbohydrate-deficient transferrin (r = 0.366; all significant at p < 0.05). When we compared results between EtG levels and the HTOL/HIAA ratio, 68.8% (n = 119) of those positive for EtG did not have elevated values for the HTOL/HIAA ratio. Thirty-one percent (31.2%) of these 119 subjects were positive for both parameters, but of those negative for EtG, only 4.4% had an elevated HTOL/HIAA ratio.

CONCLUSIONS

EtG is a good candidate for a sensitive, specific, and reliable marker of recent alcohol intake. The complementary use of this marker with other biological state markers should significantly improve treatment outcome and therapy effectiveness and reduce costs.