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

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.

Measurement of direct ethanol metabolites suggests higher rate of alcohol use among pregnant women than found with the AUDIT--a pilot study in a population-based sample of Swedish women

OBJECTIVES

The objective of the study was to investigate whether biomarkers of alcohol consumption would provide additional information to the use of a validated alcohol questionnaire in pregnant women.

STUDY DESIGN

One hundred three pregnant women were included in the study. The women completed the Alcohol Use Disorders Identification Test (AUDIT) questionnaire, and a urine and hair sample was collected. The urine samples were used for determination of ethyl glucuronide (EtG) and ethyl sulfate and the hair samples for EtG and fatty acid ethyl esters (FAEE).

RESULTS

Twenty-six women (25.2%) were identified as possible alcohol consumers by the combined use of AUDIT and direct ethanol metabolites. Seven subjects had EtG or FAEE levels in hair highly suspicious of heavy drinking, but only 1 of these were positive according to the AUDIT questionnaire

CONCLUSION

The combined use of the AUDIT questionnaire and direct ethanol metabolites appear to identify more potential alcohol consumers among pregnant women than does the sole use of the AUDIT questionnaire.

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.

Kinetics in serum and urinary excretion of ethyl sulfate and ethyl glucuronide after medium dose ethanol intake

The direct ethanol metabolites, ethyl glucuronide (EtG) and ethyl sulfate (EtS), are of increasing importance for clinical and forensic applications, but there are only few studies on the kinetics of EtG in serum and none on EtS. In this study, 13 volunteers (social drinkers) drank ethanol in the form of white wine to reach a blood alcohol concentration of 0.51 +/- 0.17 g/kg, and blood and urine samples were analyzed for EtG and EtS simultaneously by chromatography-tandem mass spectrometry (LC-MS/MS). Mean peak serum EtG and EtS concentrations were 2.9 +/- 1.3 and 2.8 +/- 1.6 micromol/l, respectively, and were reached between 4.0 +/- 0.9 h after the start of drinking (3.0 +/- 0.5 h for EtS). The mean time differences between reaching maximum blood ethanol levels and serum metabolite levels were 2.3 +/- 0.9 h for EtG and 1.2 +/- 0.5 h for EtS. In the last blood samples collected (10-11 h after the start of drinking), 11 (of 13) volunteers were still positive for EtG in serum, whereas only 2 were positive for EtS. In the serum of one female person, no EtS was detectable at any time; however, it was excreted in the urine in (low) concentrations. Ethanol was detectable in the serum for up to 8.6 h after the start of drinking, whereas EtG and EtS were detectable up to more than 5.8 h (EtG) and 4.0 h (EtS), respectively. Mean peak urinary concentrations were 401 +/- 232 micromol/l for EtG and 266 +/- 153 micromol/l for EtS, and mean peak levels were reached 6.2 +/- 0.9 h (EtG) and 5.3 +/- 1.2 h (EtS) after the start of drinking. Maximum concentrations of EtG and EtS in serum showed a wide interindividual variation and could not be correlated to the maximum blood ethanol concentrations. Correlations (p < 0.001, Kendall's Tau b) were found when comparing pairs of parameters, but mostly involved areas under the curve (AUC) of metabolites or of ethanol; one correlation linked the peak concentrations of EtG and EtS in urine.

Determination of ethyl sulfate--a marker for recent ethanol consumption--in human urine by CE with indirect UV detection

A CE method for the determination of the ethanol consumption marker ethyl sulfate (EtS) in human urine was developed. Analysis was performed in negative polarity mode with a background electrolyte composed of 15 mM maleic acid, 1 mM phthalic acid, and 0.05 mM cetyltrimethylammonium bromide (CTAB) at pH 2.5 and indirect UV detection at 220 nm (300 nm reference wavelength). This buffer system provided selective separation conditions for EtS and vinylsulfonic acid, employed as internal standard, from urine matrix components. Sample pretreatment of urine was minimized to a 1:5 dilution with water. The optimized CE method was validated in the range of 5-700 mg/L using seven lots of urine. Intra- and inter-day precision and accuracy values, determined at 5, 60, and 700 mg/L with each lot of urine, fulfilled the requirements according to common guidelines for bioanalytical method validation. The application to forensic urine samples collected at autopsies as well as a successful cross-validation with a LC-MS/MS-based method confirmed the overall validity and real-world suitability of the developed expeditious CE assay (sample throughput 130 per day).

Ethyl glucuronide and ethyl sulphate determination in serum by liquid chromatography–electrospray tandem mass spectrometry

BACKGROUND

Ethyl glucuronide (EtG) and ethyl sulphate (EtS) are two ethanol metabolites that can be detected in serum up to 8 h after ethanol elimination. Their presence is therefore indicative of recent ethanol consumption in case of delayed sampling after an event (e.g. car crash).

METHODS

A LC-ESI-MS-MS method for the determination of EtG and EtS in serum was developed and validated. Two product ions together with the parent ions were monitored for identification. Pentadeuterated-EtG was used as internal standard.

RESULTS

Excellent linearity for EtG (from 0.22 to 45 micromol/l) and EtS (from 0.40 to 80 micromol/l) was observed (r(2)>or=0.9998). LOD and LLOQ were 0.04 and 0.20 micromol/l for EtG and 0.08 and 0.40 micromol/l for EtS, respectively. Accuracy (bias) and precision (relative standard deviation), studied at four different quality control levels, were always better than 7%. Matrix effects were found to be negligible. The method was applied to several samples obtained from known alcoholics and social drinkers.

CONCLUSIONS

A sensitive and specific determination of EtG and EtS in serum samples was achieved despite a simple and fast sample preparation. To our knowledge, this is the first fully validated method for the simultaneous determination of the two alcohol metabolites in serum.

Determination of glucuronidated 5-hydroxytryptophol (GTOL), a marker of recent alcohol intake, by ELISA technique

OBJECTIVES

To compare markers of alcohol consumption.

DESIGN AND METHODS

Measurement of urinary ethyl glucuronide, 5-hydroxytryptophol, 5-hydroxytryptophol glucuronide, 5-hydroxyindole acetic acid in 10 patients during alcohol withdrawal.

RESULTS

5-Hydroxytryptophol glucuronide was measured by ELISA with good analytical precision, its diagnostic specificity and sensitivity was better than that of 5-hydroxytryptophol and its correlation was closer to ethyl glucuronide than to 5-hydroxytryptophol.

CONCLUSION

Determination of 5-hydroxytryptophol glucuronide by ELISA offers promising results in detection of previous alcohol consumption.

Effects of lactate and acetate on the determination of serum ethyl glucuronide by CZE

The analysis of ethyl glucuronide (EtG), a marker of recent alcohol consumption, in serum with an optimized CZE assay is reported. The method uses a 0.1-mm id fused-silica capillary of 50 cm effective length that is coated with linear polyacrylamide, a pH 4.4 nicotinic acid/epsilon-aminocaproic acid (EACA) BGE, reversed polarity and indirect analyte detection. The assay is based on a 1:1 dilution of serum with deionized water and has LODs for EtG, lactate and acetate of 3.8 x 10(-7) M, 2.60 x 10(-6 )M and 2.18 x 10(-6 )M, respectively. Separation of EtG from endogenous macro- and microcomponents (anionic serum components of high and low concentration, respectively) and its quantification are shown to be possible for a wide range of lactate (stacker) and acetate (destacker) concentrations, macrocomponents that have an impact on the CZE behavior of EtG and that change after intake of ethanol. The assay has been successfully applied to the analysis of EtG, lactate and acetate in (i) sera of volunteers that ingested known amounts of alcohol and (ii) samples of patients that were classified (teetotalers and social drinkers vs. alcohol abusers) via analysis of carbohydrate-deficient transferrin.

Proton nuclear magnetic resonance spectroscopic determination of ethanol-induced formation of ethyl glucuronide in liver

Ethyl glucuronide (ethyl-beta-D-6-glucosiduronic acid, EtG), a unique metabolite of ethanol, has received much recent attention as a sensitive and specific biological marker of ethanol consumption. Formed in the liver via conjugation of ethanol with activated glucuronate, EtG remains detectable in serum, plasma, and hair for days after ethanol abuse. Thus far, gas chromatography-mass spectrometry and enzyme-linked immunosorbent assays have been developed to detect trace quantities of EtG for forensic purposes, but reports of the nuclear magnetic resonance (NMR) properties of EtG have been scarce. Herein we present the first report of EtG determination using proton NMR spectroscopy. We collected 700-MHz proton spectra of liver extracts from rats treated with a 4-day binge ethanol protocol (average ethanol dose: 8.6g/kg/day). An unexpected signal (triplet, 1.24 ppm) appeared in ethanol-treated liver extracts but not in control samples; based on chemical shift and multiplicity, we suspected EtG. We observed quantitative hydrolysis of the unknown species to ethanol while incubating our samples with beta-glucuronidase, confirming that the methyl protons of EtG were responsible for the triplet at 1.24 ppm. This study demonstrates that proton NMR spectroscopy is capable of detecting EtG and that future NMR-based metabolomic studies may encounter this metabolite of ethanol.

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

AIMS

This study aims to investigate the relationship between ethanol daily intake (EDI) and the levels of ethyl glucuronide in hair.

DESIGN

Ethyl glucuronide concentration was determined in hair samples from different classes of ethanol drinkers and results were compared with the reported information about drinking habits.

SETTING

Pavia, Italy.

PARTICIPANTS

Twenty-two known alcoholics, 21 volunteers self-reporting an EDI from 2 to 60 g, and seven teetotallers were involved in this study.

MEASUREMENTS

Ethyl glucuronide determination in hair samples was performed by liquid chromatography-tandem mass spectrometry (limit of detection: 2 pg/mg, lower limit of quantification: 3 pg/mg).

FINDINGS

Current known alcoholics (n = 21) had ethyl glucuronide hair concentration in the range 4.0-434.7 pg/mg (average: 62.8, median 37.4 pg/mg); ethyl glucuronide was not detected in hair samples from teetotallers (n = 7); all volunteers reporting an EDI of at least 30 g ('non-moderate drinkers' according to the US Department of Health and Human Services) tested positive for ethyl glucuronide (cut-off: 4 pg/mg). All volunteers declaring an ethanol daily intake higher than 40 g ('heavy drinkers' according to the World Health Organization, Regional Committee for Europe) tested positive for this compound (cut-off: 5 pg/mg). The application of a cut-off of either 4 pg/mg or 5 pg/mg resulted in one false positive, coming from a volunteer asserting an ethanol daily intake of 30 g. No false negatives were found.

CONCLUSIONS

The concentration of ethyl glucuronide in hair appears to correlate with EDI.

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.

Distribution of ethyl glucuronide in rib bone marrow, other tissues and body liquids as proof of alcohol consumption before death

Postmortem ethyl glucuronide (EtG) concentrations in rib bone marrow, liver, muscle, fat tissue, urine, blood and bile have been determined by LC-MS/MS. Samples have been taken from twelve corpses during autopsies. In nine corpses EtG could be detected, corresponding blood ethanol concentrations (BAC) were 0.04-0.37 g%. In three cases, no EtG was found; two of these cases showed postmortem BACs - possibly due to putrefaction - of 0.01 and 0.1g%. In rib bone marrow, which is easily accessible during autopsy, EtG concentrations (0.77-9.36 microg/g) have been lower than in blood (2.24-20.46 microg/mL) in eight of nine cases and comparable or higher than in muscle tissue. Therefore, rib bone marrow has been found suitable as matrix for EtG determination. The highest EtG concentrations have been found in urine in all but one case, where the resorption of ethanol had been incomplete. Second highest EtG concentrations have been detected in liver samples. In two cases with putrefaction, EtG could not be detected. In these cases, the detectable ethanol might have been produced partially or in total by postmortem fermentation. However, instability of EtG during putrefaction cannot be totally excluded which might result in a total loss of EtG.

Emerging Biomarkers: New Directions and Clinical Applications

This article summarizes content proceedings of a symposium held at the 2004 Research Society on Alcoholism Scientific Annual Meeting in Vancouver, Canada. The chairs were Friedrich M. Wurst and Raye Litten. The presentations were (1) Introduction, by Raye Litten; (2) Direct Ethanol Metabolites--On the Threshold From Science to Routine Use, by Friedrich M. Wurst; (3) Sialic Acid Index of Plasma Apolipoprotein J (SIJ) as a Viable Marker for Chronic Alcohol Consumption, by Philippe Marmillot; (4) The Emergence of Ethyl Glucuronide (EtG) Testing as a Tool in Monitoring Healthcare Professionals, by Gregory E. Skipper; (5) Application of Biomarkers for Alcohol Use Disorders in Clinical Practice, by Tim Neumann; (6) Utility of Biomarkers in Assessing the Efficacy of Medications for Treating Alcoholism, by Marty Javors; and (7) Discussion, by Raye Litten.

The role of acetaldehyde in the neurobehavioral effects of ethanol: A comprehensive review of animal studies

Acetaldehyde has long been suggested to be involved in a number of ethanol's pharmacological and behavioral effects, such as its reinforcing, aversive, sedative, amnesic and stimulant properties. However, the role of acetaldehyde in ethanol's effects has been an extremely controversial topic during the past two decades. Opinions ranged from those virtually denying any role for acetaldehyde in ethanol's effects to those who claimed that alcoholism is in fact "acetaldehydism". Considering the possible key role of acetaldehyde in alcohol addiction, it is critical to clarify the respective functions of acetaldehyde and ethanol molecules in the pharmacological and behavioral effects of alcohol consumption. In the present paper, we review the animal studies reporting evidence that acetaldehyde is involved in the pharmacological and behavioral effects of ethanol. A number of studies demonstrated that acetaldehyde administration induces a range of behavioral effects. Other pharmacological studies indicated that acetaldehyde might be critically involved in several effects of ethanol consumption, including its reinforcing consequences. However, conflicting evidence has also been published. Furthermore, it remains to be shown whether pharmacologically relevant concentrations of acetaldehyde are achieved in the brain after alcohol consumption in order to induce significant effects. Finally, we review current evidence about the central mechanisms of action of acetaldehyde.

Assessment of UDP-glucuronosyltransferase catalyzed formation of ethyl glucuronide in human liver microsomes and recombinant UGTs

While ethanol is primarily metabolized to acetaldehyde and acetic acid via alcohol dehydrogenase, a minor but increasingly important pathway in the field of forensic science involves the conjugation of glucuronic acid to form an ethyl glucuronide (EtG) metabolite. The kinetics of ethyl glucuronide formation were examined in human liver microsomes (HLM) and recombinant UDP-glucuronosyltransferases (UGTs). The metabolite exhibited a relatively slow rate of formation in a human liver microsome mix of 75.4 pmol/(min/mg). Further investigation identified multiple UGT isoforms to be responsible for catalyzing the addition of glucuronic acid to ethanol, with UGT1A1 and 2B7 being the two most prevalent isoforms. Co-incubation with bilirubin or 3'-azido-3'-deoxythymidine (UGT1A1 and 2B7 inhibitors, respectively) inhibited the greatest amount of ethyl glucuronide formation, though other UGT inhibitors also showed some effect. Enzyme kinetics were performed in human liver microsomes and recombinant UGT enzymes. The apparent Km (Km app) and Vmax values were determined to be 0.17+/-0.08 mM and 75.98+/-5.63 pmol/(min/mg) (human liver microsomes), 0.03+/-0.01 mM and 25.22+/-3.45 pmol/(min/mg) (UGT1A1), and 0.11+/-0.04 mM and 52.03+/-9.8 pmol/(min/mg) (UGT2B7). Thus, it appears that multiple UGTs are responsible for the formation of ethyl glucuronide and that any functional differences in the enzymology underlying ethyl glucuronide formation would most likely be masked by a combination of other enzymatic pathways.

Direct determination of the ethanol metabolites ethyl glucuronide and ethyl sulfate in urine by liquid chromatography/electrospray tandem mass spectrometry

A liquid chromatography/electrospray tandem mass spectrometry (LC/ESI-MS/MS) method for the determination in urine samples of two ethanol metabolites, ethyl glucuronide (EtG) and ethyl sulfate (EtS), was developed and validated. Pentadeuterated EtG was used as internal standard for both EtG and EtS. In addition to the surviving ions, two MS/MS reactions were monitored for each analyte, with the deprotonated molecule as precursor ion: m/z 221 --> 75, m/z 221 --> 85 (EtG), and m/z 125 --> 97, m/z 125 --> 80 (EtS). Sample pretreatment, though very simple and rapid (1:50 water dilution and centrifugation of 50 muL of urine), was found to contain the occurrence of matrix effects. The method was accurate and precise over the linear dynamic range (0.05-10 mg/L). The analytes were stable in frozen urine for at least 1 month. The assay was applied to several authentic urine samples from social drinkers and to alcoholic beverages.

Forensic confirmatory analysis of ethyl sulfate--a new marker for alcohol consumption--by liquid-chromatography/electrospray ionization/tandem mass spectrometry

Ethyl sulfate (EtS)--a new direct marker for ethanol intake besides ethyl glucuronide (EtG) and others--was detected in urine samples by electrospray ionization tandem mass-spectrometry (LC-ESI-MS/MS). Ethyl sulfate sodium salt was used for method development, yielding a precursor [M - H]- m/z 125 and product ions m/z 97 [HSO4]- and m/z 80 [SO3]-. Pentadeuterated EtS (D5-EtS) was synthesized by esterification of sulfuric acid with anhydrous hexadeutero ethanol ([M - H]- m/z 130, product ions m/z 98 [DSO4]- and m/z 80 [SO3]-). After addition of D5-EtS and D5-EtG, urine samples were analyzed by direct injection into the gradient LC-MS/MS system. Analysis was performed in accordance with forensic guidelines for confirmatory analysis using one precursor and two product ions. EtS has been detected (in addition to EtG) in the urine samples of nine volunteers after drinking sparkling wine containing between 9 and 49 g of ethanol. Both EtS and EtG could be detected up to 36 h after consumption of alcohol. The excretion profile was found to be similar to that of EtG. No EtS was found in teetotalers' urine samples. Method validation parameters are presented. EtS was stable in urine upon storage up to twenty days at room temperature. In addition to EtG, EtS can be used to detect recent alcohol consumption, thus providing a second marker for the time range of up to approximately one day after elimination of ethanol from urine samples. The determination of EtS can be used in addition to EtG as proof of ethanol consumption in workplace monitoring programs.

Ethyl glucuronide: a biomarker to identify alcohol use by health professionals recovering from substance use disorders

AIMS

Physicians recovering from substance-related disorders are usually allowed to return to practice if they agree to remain abstinent from drugs, including alcohol, and to undergo random urine testing. Over 9000 physicians are currently involved in such monitoring programs in the US. To date, it has been difficult to adequately monitor abstinence from alcohol due to the short half-life of alcohol and no other highly specific marker. Ethyl glucuronide (EtG), a direct metabolite of alcohol, offers an extended window for assessment of drinking status (up to 5 days). Our aim was to assess the potential value of EtG testing in abstinence-based monitoring programs.

PATIENTS AND METHODS

Urine samples were obtained from 100 participants in a physician monitoring program and additional samples were subsequently obtained 'for cause', 'to verify positive urine alcohol, when drinking was denied' and 'in high risk individuals'. All participants had signed contracts agreeing to remain abstinent from mood-altering drugs, including alcohol, and had agreed to random urine testing. EtG was determined using LC/MS-MS in addition to standard testing. The main outcome measure were urine specimens positive for EtG versus those positive based on standard testing for alcohol and other drugs.

RESULTS

Among the initial 100 random samples collected, no sample was positive for alcohol using standard testing; however, seven were positive for EtG (0.5-196 mg/l), suggesting recent alcohol use. Subsequent EtG testing was performed clinically during the course of monitoring. Of the 18 tests performed to date, eight of eight tests performed 'for cause' were positive for EtG but negative for all other drugs including urine alcohol. All eight were confirmed positive by self reported drinking by the patient when confronted regarding the positive test result. Of six tests performed to 'confirm a positive urine alcohol' two were positive for EtG and confirmed positive by self reported drinking. For the other four samples, especially as two are from a diabetic, in vitro fermentation of ethanol is discussed.

CONCLUSIONS

These data suggest that physicians in monitoring programs have a higher rate of unrecognized alcohol use than previously reported. Incorporation of EtG testing into alcohol abstinence monitoring can strengthen these programs.

On Sensitivity, Specificity, and the Influence of Various Parameters on Ethyl Glucuronide Levels in Urine???Results From the WHO/ISBRA Study

BACKGROUND

Ethyl glucuronide (EtG), a direct ethanol metabolite, seems to meet the need for a sensitive and specific marker for monitoring recent alcohol consumption in different settings. Our aim was to study sensitivity, specificity, and the influence of various parameters on EtG levels in urine.

PATIENTS AND METHODS

Urine samples for a total of 453 patients (373 male, 80 female) were statistically analyzed. The mean age was 37.1 years (median 36, SD 12.59), body mass index was 24.7, total ethanol consumed last month was 1817.66 g (each median), and 80 patients reported cannabis use within the last 30 days. Determination of EtG was performed with a liquid chromatography-tandem mass spectrometry method with deuterium-labeled EtG as internal standard.

RESULTS

For EtG in urine, a good correlation was found with other state markers and days of sobriety. In a regression analysis, age, gender, marijuana use, kidney disease, and total grams of ethanol consumed last month were the variables that significantly influenced EtG levels in contrast to race, smoking, body mass index, cirrhosis of liver, age began drinking regularly, packs of cigarettes smoked last month, and total body water. Furthermore, in a receiver operating characteristic curve analysis to distinguish between nondrinkers and individuals sober > 4 days versus individuals drinking in the recent 4 days, area under the curve was 0.834. At a cutoff of 0.145 mg/liter, sensitivity was 83.5% and specificity 68.3%. A receiver operating characteristic curve was calculated for lifetime alcohol abuse or dependence against those who had never been abusers or dependent. In this case, subjects were either never dependent or lifetime dependent, but those currently dependent were excluded. The resulting area under the curve was 0.694. At a cutoff of 0.145 mg/liter, sensitivity was 73.8% and specificity 60.3%. For those with a self-reported sobriety of less than 24 hr, the area under the curve was 0.899, sensitivity was 90.8%, and specificity was 76.5% at a cutoff of 0.435 mg/liter when we calculated nondrinkers and light drinkers against heavy drinkers and drinkers needing treatment. Cannabis-using patients showed significant differences with regard to almost all state markers when compared with nonconsuming subjects.

CONCLUSIONS

Age, gender, marijuana use, kidney disease, and total grams of ethanol consumed last month should be taken into consideration when interpreting results of EtG in urine. Sensitivity and specificity seem promising. Cannabis use can be regarded as an indicator for other serious mental problems in alcohol-using subjects.