Phosphatidylethanol in blood as a marker of chronic alcohol use: a systematic review and meta-analysis

Alternative sampling strategies for the assessment of alcohol intake of living persons

Monitoring of alcohol consumption by living persons takes place in various contexts, amongst which workplace drug testing, driving under the influence of alcohol, driving licence regranting programs, alcohol withdrawal treatment, diagnosis of acute intoxication or fetal alcohol ingestion. The matrices that are mostly used today include blood, breath and urine. The aim of this review is to present alternative sampling strategies that allow monitoring of the alcohol consumption in living subjects. Ethanol itself, indirect (carbohydrate deficient transferrin, CDT%) as well as direct biomarkers (ethyl glucuronide, EtG; ethyl sulphate, EtS; fatty acid ethyl esters, FAEEs and phosphatidylethanol species, PEths) of ethanol consumption will be considered. This review covers dried blood spots (CDT%, EtG/EtS, PEths), dried urine spots (EtG/EtS), sweat and skin surface lipids (ethanol, EtG, FAEEs), oral fluid (ethanol, EtG), exhaled breath (PEths), hair (EtG, FAEEs), nail (EtG), meconium (EtG/EtS, FAEEs), umbilical cord and placenta (EtG/EtS and PEth 16:0/18:1). Main results, issues and considerations specific to each matrix are reported. Details about sample preparation and analytical methods are not within the scope of this review.

Characterization of the Pharmacokinetics of Phosphatidylethanol 16:0/18:1 and 16:0/18:2 in Human Whole Blood After Alcohol Consumption in a Clinical Laboratory Study

BACKGROUND

The purpose of this study was to characterize the pharmacokinetics of 2 homologues of phosphatidylethanol (PEth) and their combined total in uncoagulated, whole blood samples taken from participants in a human clinical laboratory study after consumption of low doses of ethanol (EtOH).

METHODS

As part of a larger study, 14 male and 13 female participants received either 0.25 or 0.50 g/kg oral doses of EtOH during a 15-minute period. Blood samples were collected before and throughout 6 hours after each EtOH dose on the day of consumption and then every 3 days during the next 14 days. PEth 16:0/18:1 and PEth 16:0/18:2 levels were quantified in blood samples by HPLC/MS/MS and reported separately or as their combined total (combined PEth). Breath alcohol concentrations (BrACs) were measured concurrently with each blood collection. Transdermal alcohol concentrations were measured every 30 minutes during the entire 22-day study to confirm the absence of drinking during a 7-day period before and the 14-day period after EtOH consumption.

RESULTS

(i) Single doses of 0.25 and 0.50 g EtOH/kg produced proportional increases in BrAC and combined PEth levels of all participants; (ii) the areas under the curve (AUCs) for each participant's BrAC levels during the 6-hour period after EtOH administration were correlated with AUCs of cPEth (calculated as the AUC of the increase above baseline for combined PEth); (iii) the mean half-life of combined PEth, determined during the 14-day period after EtOH consumption, was 4.6 ± 3.5 (SD) days (range: 1.0 to 13.1 days).

CONCLUSIONS

Combined PEth is a sensitive biomarker for the identification of relatively low levels of EtOH consumption. The measurement of these 2 homologues may provide additional sensitivity to identify low levels of drinking.

Bioanalytical procedures and developments in the determination of alcohol biomarkers in biological specimens

Excessive alcohol consumption is a global problem, and consequently its evaluation is of great clinical and forensic interest. Alcohol biomarkers have been the focus of several research works in the past decades, with new compounds being studied in more recent years. The main objective of this review is to discuss topics for an analyst to consider when evaluating alcohol consumption through the analysis of alcohol biomarkers in biological specimens. For this, existing alcohol biomarkers will be reviewed, including carbohydrate-deficient transferrin, 5-hydroxytryptophol, ethanol, hemoglobin-associated acetaldehyde, fatty acid ethyl esters, ethyl glucuronide, ethyl sulfate and phosphatidylethanol. Additionally, their potential will be discussed, as well as analytical considerations, main challenges, limitations, data interpretation and existing methodologies for their determination in biological specimens.

Quantification of phosphatidylethanol 16:0/18:1, 18:1/18:1, and 16:0/16:0 in venous blood and venous and capillary dried blood spots from patients in alcohol withdrawal and control volunteers

Phosphatidylethanol species (PEths) are promising biomarkers of alcohol consumption. Here, we report on the set-up, validation, and application of a novel UHPLC-ESI-MS/MS method for the quantification of PEth 16:0/18:1, PEth 18:1/18:1, and PEth 16:0/16:0 in whole blood (30 μL) and in venous (V, 30 μL) or capillary (C, 3 punches (3 mm)) dried blood spots (DBS). The methods were linear from 10 (LLOQ) to 2000 ng/mL for PEth 16:0/18:1, from 10 (LLOQ) to 1940 ng/mL for PEth 18:1/18:1, and from 19 (LLOQ) to 3872 ng/mL for PEth 16:0/16:0. Extraction efficiencies were higher than 55% (RSD < 18%) and matrix effects compensated for by IS were between 77 and 125% (RSD < 10%). Accuracy, repeatability, and intermediate precision fulfilled acceptance criteria (bias and RSD below 13%). Validity of the procedure for determination of PEth 16:0/18:1 in blood was demonstrated by the successful participation in a proficiency test. The quantification of PEths in C-DBS was not significantly influenced by the hematocrit, punch localization, or spot volume. The stability of PEths in V-DBS stored at room temperature was demonstrated up to 6 months. The method was applied to authentic samples (whole blood, V-DBS, and C-DBS) from 50 inpatients in alcohol withdrawal and 50 control volunteers. Applying a cut-off value to detect inpatients at 221 ng/mL for PEth 16:0/18:1 provided no false positive results and a good sensitivity (86%). Comparison of quantitative results (Bland-Altman plot, Passing-Bablok regression, and Wilcoxon signed rank test) revealed that V-DBS and C-DBS were valid alternatives to venous blood for the detection of alcohol consumption.

Comparison of self-reported alcohol use with the alcohol biomarker phosphatidylethanol among young people in northern Tanzania

BACKGROUND

The one-month Time Line Follow Back calendar (TLFB) and the Alcohol Use Disorders Identification Test (AUDIT) are used to collect self-reported alcohol intake data. We compared these instruments with the alcohol biomarker phosphatidylethanol (PEth) among young-people in northern Tanzania.

METHODS

AUDIT and TLFB were applied in a cross-sectional study of 202 young people (18-24 years), who reported using alcohol during the past year (103 male casual labourers; 99 college students). We assayed whole blood for PEth 16:0/18:1, using liquid chromatography-tandem mass spectrometry.

RESULTS

For both self-report methods, alcohol consumption was high, particularly among men (e.g. a median of 54 drinks per month in labourers), and about half of male students (48%) reported hazardous or harmful levels of drinking (AUDIT ≥8). Almost half (49%) of participants were PEth-positive (median concentration 0.03μmol/L). There were significant positive correlations between reported total alcohol intake and PEth concentration in males (Spearman's correlation rs=0.65 in college students and rs=0.57 in casual labourers; p<0.001). Self-reported use in the past month was a sensitive marker of having a positive PEth result (≥0.01μmol/L) with 89% of those with a PEth positive result reporting alcohol use, and this was similar in all groups. The proportion of those with AUDIT scores ≥8 and AUDIT-C scores ≥6 among those with a high cut-off positive PEth result (≥0.30μmol/L) ranged between 94 and 100%.

CONCLUSION

TLFB and AUDIT are sensitive measures to detect heavy alcohol use among young-people in northern Tanzania. They can be used to identify young people who may benefit from alcohol-focused interventions.

Validation of the MINI (DSM IV) Tool for the Assessment of Alcohol Dependence among Young People in Northern Tanzania Using the Alcohol Biomarker Phosphatidylethanol (PEth)

The alcohol dependence section of the Mini International Neuropsychiatric Interview questionnaire (MINI) has not been evaluated in young Africans. We applied the MINI in a cross-sectional study of 202 alcohol users from northern-Tanzania, aged 18-24 years (103 male casual workers and 99 students), and validated it against phophatidylethanol (PEth) at a cut-off suggesting heavy chronic alcohol use (≥0.30 µmol/L). Blood was assayed for PEth (16:0/18:1-subform) by liquid chromatography-tandem mass spectrometry. The MINI dependence criteria (≥3 positive responses) were met by 39% participants although their PEth levels were low. Contrary, many young people with high PEth levels were not classified as dependent. The sensitivity of the MINI ranged from 0% to 69% (female students and male workers, respectively) and specificity from 52% to 85% (workers and female students, respectively). The highest AUROC (0.68) occurred with a cut-off of ≥4 positive responses. A modified MINI with three affirmative responses to five questions increased specificity to 92%-97%; however, sensitivity remained low. The performance of the MINI in detecting dependence among young people from northern-Tanzania is unsatisfactory. Specificity was improved using a modified version but sensitivity remained low. An accurate tool for the diagnosis of alcohol dependence is needed for epidemiological and clinical purposes.

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.

A New Genomewide Association Meta-Analysis of Alcohol Dependence

BACKGROUND

Conventional meta-analysis based on genetic markers may be less powerful for heterogeneous samples. In this study, we introduced a new meta-analysis for 4 genomewide association studies on alcohol dependence that integrated the information of putative causal variants.

METHODS

A total of 12,481 subjects in 4 independent cohorts were analyzed, including 1 European American cohort (1,409 cases with alcohol dependence and 1,518 controls), 1 European Australian cohort (a total of 6,438 family subjects with 1,645 probands), 1 African American cohort from SAGE + COGA (681 cases and 508 controls), and 1 African American cohort from Yale (1,429 cases and 498 controls). The genomewide association analysis was conducted for each cohort, and then, a new meta-analysis was performed to derive the combined p-values. cis-Acting expression of quantitative locus (cis-eQTL) analysis of each risk variant in human tissues and RNA expression analysis of each risk gene in rat brain served as functional validation.

RESULTS

In meta-analysis of European American and European Australian cohorts, we found 10 top-ranked single nucleotide polymorphisms (SNPs) (p < 10(-6) ) that were associated with alcohol dependence. They included 6 at SERINC2 (3.1 × 10(-8) ≤ p ≤ 9.6 × 10(-8) ), 1 at STK40 (p = 1.3 × 10(-7) ), 2 at KIAA0040 (3.3 × 10(-7) ≤ p ≤ 5.2 × 10(-7) ), and 1 at IPO11 (p = 6.9 × 10(-7) ). In meta-analysis of 2 African American cohorts, we found 2 top-ranked SNPs including 1 at SLC6A11 (p = 2.7 × 10(-7) ) and 1 at CBLN2 (p = 7.4 × 10(-7) ). In meta-analysis of all 4 cohorts, we found 2 top-ranked SNPs in PTP4A1-PHF3 locus (6.0 × 10(-7) ≤ p ≤ 7.2 × 10(-7) ). In an African American cohort only, we found 1 top-ranked SNP at PLD1 (p = 8.3 × 10(-7) ; OR = 1.56). Many risk SNPs had positive cis-eQTL signals, and all these risk genes except KIAA0040 were found to express in both rat and mouse brains.

CONCLUSIONS

We found multiple genes that were significantly or suggestively associated with alcohol dependence. They are among the most appropriate for follow-up as contributors to risk for alcohol dependence.

Biomolecules and Biomarkers Used in Diagnosis of Alcohol Drinking and in Monitoring Therapeutic Interventions

BACKGROUND

The quantitative, measurable detection of drinking is important for the successful treatment of alcohol misuse in transplantation of patients with alcohol disorders, people living with human immunodeficiency virus that need to adhere to medication, and special occupational hazard offenders, many of whom continually deny drinking. Their initial misconduct usually leads to medical problems associated with drinking, impulsive social behavior, and drunk driving. The accurate identification of alcohol consumption via biochemical tests contributes significantly to the monitoring of drinking behavior.

METHODS

A systematic review of the current methods used to measure biomarkers of alcohol consumption was conducted using PubMed and Google Scholar databases (2010-2015). The names of the tests have been identified. The methods and publications that correlate between the social instruments and the biochemical tests were further investigated. There is a clear need for assays standardization to ensure the use of these biochemical tests as routine biomarkers.

FINDINGS

Alcohol ingestion can be measured using a breath test. Because alcohol is rapidly eliminated from the circulation, the time for detection by this analysis is in the range of hours. Alcohol consumption can alternatively be detected by direct measurement of ethanol concentration in blood or urine. Several markers have been proposed to extend the interval and sensitivities of detection, including ethyl glucuronide and ethyl sulfate in urine, phosphatidylethanol in blood, and ethyl glucuronide and fatty acid ethyl esters in hair, among others. Moreover, there is a need to correlate the indirect biomarker carbohydrate deficient transferrin, which reflects longer lasting consumption of higher amounts of alcohol, with serum γ-glutamyl transpeptidase, another long term indirect biomarker that is routinely used and standardized in laboratory medicine.

Alcohol intake measured by phosphatidylethanol in blood and the lifetime drinking history interview are correlated with the extent of psoriasis

BACKGROUND

Psoriasis has been reported to be associated with alcohol consumption.

OBJECTIVE

To investigate the level of alcohol intake in individuals with psoriasis and correlate intake with the extent of disease and pruritus.

METHODS

Twenty-nine outpatients (15 females and 14 males) with stable chronic plaque psoriasis of moderate severity were recruited. The Psoriasis Area and Severity Index (PASI) and the degree of pruritus (visual analogue scale) were compared with measures of drinking habits as determined by the Lifetime Drinking History (LDH), the Alcohol Use Disorders Identification Test and whole-blood phosphatidylethanol (PEth), an alcohol-specific biomarker.

RESULTS

The majority of patients were social drinkers with moderate alcohol consumption as determined by PEth and LDH. Alcohol consumption correlated significantly with the PASI score. There was no correlation between alcohol use and pruritus.

CONCLUSION

The level of alcohol consumption is correlated with the extent of psoriasis.

A comparison of the cardiometabolic profile of black South Africans with suspected non-alcoholic fatty liver disease (NAFLD) and excessive alcohol use

Excessive alcohol use and non-alcoholic fatty liver disease (NAFLD) are putative cardiovascular disease risk factors. In order to ease the identification of these conditions on primary health care level, we aimed to determine and compare the demographic and cardiometabolic characteristics of excessive alcohol users and those with suspected NAFLD in black South Africans. In the Prospective Urban Rural Epidemiology study (North West Province, South Africa, N = 2021, collected in 2005) we selected 338 participants, namely: 1) alcohol users (N = 143) reporting 'yes' to alcohol intake, with high gamma-glutamyl transferase (GGT) ≥80 U/L and a percentage carbohydrate deficient transferrin (%CDT) ≥2%; 2) non-alcohol users (N = 127) self-reporting 'no' to alcohol intake with GGT ≤30 U/L and %CDT ≤2%; and 3) NAFLD group (N = 68) who were non-drinkers with GGT levels ≥60 U/L and %CDT ≤ 2%. The demographics indicated that the alcohol users were mostly men (73%) with a body mass index (BMI) of 19.8 (15.2-27.3) kg/m(2), 90% of which were smokers. Systolic blood pressure (SBP) of alcohol users significantly correlated with high-density lipoprotein cholesterol (HDL-C) (β = 0.24; p = 0.003) and waist circumference (WC) (β = 0.22; p = 0.006). Non-alcohol users were mostly women (84%) with a BMI of 26.0 (18.0-39.2) kg/m(2) and blood pressure in this group related positively with triglycerides. The NAFLD group were also mostly women (72%) with a comparatively larger WC (p < 0.001) and an adverse metabolic profile (total cholesterol: 5.55 ± 1.69 mmol/L; glycosylated hemoglobin: 6.03 (4.70-9.40) %). Diastolic blood pressure in the NAFLD group associated positively with WC (β = 0.27; p = 0.018). We therefore found disparate gender and cardiometabolic profiles of black South Africans with suspected NAFLD and excessive alcohol use. The described profiles may aid health care practitioners in low resource settings when using these crude screening measures of gender, obesity indices (and self-reported alcohol use) to identify individuals at risk.

Alcohol intake, hypertension development and mortality in black South Africans

BACKGROUND

Excessive alcohol intake is a risk factor for cardiovascular disease (CVD) and predicts cardiovascular and all-cause mortality. We determined which alcohol marker (self-reported alcohol intake, gamma-glutamyltransferase (GGT) or percentage carbohydrate deficient transferrin (%CDT)) relates best with mortality and predicts hypertension development over five years in black South Africans.

DESIGN

This was a longitudinal study as part of the PURE (Prospective Urban and Rural Epidemiology) study in the North West Province, South Africa.

METHOD

We included 2010 participants and followed 1471 participants. Over five years, 230 deaths occurred, of which 66 were cardiovascular-related. At enrolment, participants completed questionnaires on alcohol intake (yes, for former and current use; no, for alcohol never used). We measured blood pressure, collected blood samples and measured GGT and %CDT.

RESULTS

When comparing hazard ratios (HRs) of self-report, GGT and %CDT, we found that only GGT predicted cardiovascular (HR = 2.76 (1.49-5.12)) and all-cause mortality (HR = 2.47 (1.75-3.47)) and hypertension development ((HR = 1.31 (1.06-1.62)). Participants self-reporting yes for alcohol intake had a 30% increased risk of developing hypertension (HR = 1.30 (1.07-1.60)) but not an increased risk for mortality. When adding both GGT and self-report in the prediction model for hypertension, only self-reporting of alcohol was significant (HR = 1.24 (1.01-1.53)). The alcohol marker, %CDT, did not show any significant association with mortality or hypertension development.

CONCLUSION

GGT independently predicted cardiovascular and all-cause mortality, as well as hypertension development in black South Africans. Despite non-specificity to excessive alcohol consumption, GGT may be a useful general marker for hypertension development and mortality, also due to its significant association with self-reported alcohol intake.

Efficacy of an alcohol-focused intervention for improving adherence to antiretroviral therapy (ART) and HIV treatment outcomes - a randomised controlled trial protocol

Background

Little research has examined whether alcohol reduction interventions improve antiretroviral therapy (ART) adherence and HIV treatment outcomes. This study assesses the efficacy of an intervention for reducing alcohol use among HIV patients on ART who are hazardous/harmful drinkers. Specific aims include adapting a blended Motivational Interviewing (MI) and Problem Solving Therapy (PST) intervention for use with HIV patients; evaluating the efficacy of the intervention for reducing alcohol consumption; and assessing counsellors’ and participants’ perceptions of the intervention.

Methods/Design

A randomised controlled trial will evaluate the intervention among ART patients in public hospital-based HIV clinics in Tshwane, South Africa. We will recruit patients who are HIV-positive, on ART for at least 3 months, and classified as harmful/hazardous drinkers using the AUDIT-3. Eligible patients will be randomly assigned to one of three conditions. Patients in the experimental group will receive the MI-PST intervention to reduce harmful/hazardous alcohol use. Patients in the equal-attention wellness intervention group will receive an intervention focused on addressing health risk behaviours. Patients in the control condition will receive treatment as usual. Participants will complete an interviewer-administered questionnaire at baseline and 3, 6 and 12 months post-randomisation to assess alcohol consumption, ART adherence, physical and mental health. We will also collect biological specimens to test for recent alcohol consumption, CD4 counts and HIV RNA viral loads. The primary outcome will be reduction in the volume of alcohol consumed. Secondary outcomes include reduction in harmful/hazardous use of alcohol, reduction in biological markers of drinking, increase in adherence rates, reductions in viral loads, and increases in CD4 T-cell counts. A process evaluation will ascertain counsellors’ and participants’ perceptions of the acceptability and effectiveness of the interventions.

Discussion

We have obtained ethical approval and approval from the study sites and regional and provincial health departments. The study has implications for clinicians, researchers and policy makers as it will provide efficacy data on how to reduce harmful/hazardous alcohol consumption among HIV patients and will shed light on whether reducing alcohol consumption impacts on HIV treatment adherence and other outcomes.

Trial registration

Pan African Clinical Trials Register Number: PACTR201405000815100.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2334-14-500) contains supplementary material, which is available to authorized users.

Progress in monitoring alcohol consumption and alcohol abuse by phosphatidylethanol

For early diagnosis and therapy of alcohol-related disorders, alcohol biomarkers are highly valuable. Concerning specificity, indirect markers can be influenced by nonethanol-related factors, whereas direct markers are only formed after ethanol consumption. Sensitivity of the direct markers depends on cut-offs of analytical methods, material for analysis and plays an important role for their utilization in different fields of application. Until recently, the biomarker phosphatidylethanol has been used to differentiate between social drinking and alcohol abuse. After method optimization, the detection limit could be lowered and phosphatidylethanol became sensitive enough to even detect the consumption of low amounts of alcohol. This perspective gives a summary of most common alcohol biomarkers and summarizes new developments for monitoring alcohol consumption habits.

The validity of phosphatidylethanol in dried blood spots of newborns for the identification of prenatal alcohol exposure

BACKGROUND

Accurate identification of prenatal alcohol exposure (PAE) in the newborn period offers an opportunity for early identification of children at risk of future neurocognitive problems and the implementation of interventional approaches earlier in life. PAE newborn screening by measuring phosphatidylethanol in dried blood spot (PEth-DBS) cards is feasible, logistically easier, and more cost-efficient compared with other biomarkers. However, the sensitivity and specificity of this method have yet to be established.

METHODS

This prospective cohort study examined validity of PEth-DBS among 28 infants with PAE and 32 controls relative to maternal self-report and other biomarkers. Pregnant women were recruited from a University of New Mexico clinic and followed to early postpartum period. The composite index, which was based on self-reported measures of alcohol use and allowed to classify subjects into PAE and control groups, was the criterion measure used to estimate sensitivity and specificity of PEth-DBS.

RESULTS

The study included large proportions of patients representing ethnic minorities (7.4% American Indian, 81.7% Hispanic/Latina), low education (54.2% <high school), and unplanned pregnancy (90.0%). No differences in sociodemographic characteristics, smoking or illicit drug use were observed among the study groups. The sensitivity of maternal biomarkers (gamma glutamyltranspeptidase [GGT], % carbohydrate-deficient transferrin [%CDT], urine ethyl glucuronide [UEtG], urine ethyl sulfate [UEtS]) was low (<15%) reflecting a moderate chronic or intermittent binge pattern of drinking in this cohort. PEth-DBS demonstrated 100% specificity and the highest sensitivity (32.1%) compared with other biomarkers. A battery consisting of maternal direct ethanol metabolites (UEtG, UEtS, PEth) and newborn PEth-DBS increased sensitivity to 50% without a substantial drop in specificity (93.8%).

CONCLUSIONS

Newborn PEth-DBS is a highly specific biomarker and can facilitate accurate detection of PAE in conjunction with other biomarkers. Minimal invasiveness, ease of storage and transportation of DBS cards, absence of postcollection synthesis, cost savings, and potential integration with routine newborn screening are all unique advantages of this method.

[What ethanol metabolites as biological markers tell us about alcohol use]

Alcohol and tobacco related disorders are the two leading and most expensive causes of illness in central Europe. In addition to self reports and questionnaires, biomarkers are of relevance in diagnosis and therapy of alcohol use disorders. Traditional biomarkers such as gamma glutamyl transpeptidase or mean corpuscular volume are indirect biomarkers and are subject to influence of age, gender and non alcohol related diseases, among others.Direct ethanol metabolites such as ethyl glucuronide (EtG), ethyl sulphate (EtS) and phosphatidylethanol (PEth) are direct metabolites of ethanol, that are positive after intake of ethyl alcohol. They represent useful diagnostic tools for identifying alcohol use even more accurately than traditional biomarkers. Each of these drinking indicators remains positive in serum and urine for a characteristic time spectrum after the cessation of ethanol intake--EtG and EtS in urine up to 7 days, EtG in hair for months after ethanol has left the body. Applications include clinical routine use, emergency room settings, proof of abstinence in alcohol rehabilitation programs, driving under influence offenders, workplace testing, assessment of alcohol intake in the context of liver transplantation and fetal alcohol syndrome.