Alexandra Schröck

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.

Pharmacokinetics of GHB and detection window in serum and urine after single uptake of a low dose of GBL – an experiment with two volunteers

During the last few years γ-hydroxybutyric acid (GHB) and γ-butyrolactone (GBL) have attracted much interest as recreational drugs and knock-out drops in drug-facilitated sexual assaults. This experiment aims at getting an insight into the pharmacokinetics of GHB after intake of GBL. Therefore Two volunteers took a single dose of 1.5 ml GBL, which had been spiked to a soft drink. Assuming that GBL was completely metabolized to GHB, the corresponding amount of GHB was 2.1 g. Blood and urine samples were collected 5 h and 24 h after ingestion, respectively. Additionally, hair samples (head hair and beard hair) were taken within four to five weeks after intake of GBL. Samples were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) after protein precipitation with acetonitrile. The following observations were made: spiked to a soft drink, GBL, which tastes very bitter, formed a liquid layer at the bottom of the glass, only disappearing when stirring. Both volunteers reported weak central effects after approximately 15 min, which disappeared completely half an hour later. Maximum concentrations of GHB in serum were measured after 20 min (95 µg/ml and 106 µg/ml). Already after 4-5 h the GHB concentrations in serum decreased below 1 µg/ml. In urine maximum GHB concentrations (140 µg/ml and 120 µg/ml) were measured after 1-2 h, and decreased to less than 1 µg/ml within 8-10 h. The ratio of GHB in serum versus blood was 1.2 and 1.6.

Commentary on the Paper of Walther L. et al.: Phosphatidylethanol is Superior to CDT and GGT as an Alcohol Marker and Is a Reliable Estimate of Alcohol Consumption Level.

THE PAPER OF Walther and colleagues (2015) contributes to a timely and both from a scientific as well as clinical point of view relevant issue, namely the role of the ethanol (EtOH) metabolite phosphatidylethanol (PEth) in concert with questionnaires and biomarkers for the assessment of EtOH intake. For a better understanding of strengths, potential limitations, and future research needs, at first some aspects of the Alcohol Use Disorders Identification Test (AUDIT) and PEth are briefly recapitulated.

Improved detection of alcohol consumption using the novel marker phosphatidylethanol in the transplant setting: results of a prospective study

Phosphatidylethanol (PEth) is a new, highly specific alcohol marker. The aim of this study was to assess its diagnostic value in the liver transplant setting. In 51 pre‐ and 61 post‐transplant patients with underlying alcoholic liver disease PEth, ethanol, methanol, carbohydrate‐deficient transferrin (CDT), and ethyl glucuronide in urine (uEtG) and hair (hEtG) were tested and compared with patients’ questionnaire reports. Twenty‐eight (25%) patients tested positive for at least one alcohol marker. PEth alone revealed alcohol consumption in 18% of patients. With respect to detection of alcohol intake in the preceding week, PEth showed a 100% sensitivity. PEth testing was more sensitive than the determination of ethanol, methanol, CDT or uEtG alone [sensitivity 25% (confidence interval (CI) 95%, 7–52%), 25% (7–52%), 21% (6–45%) and 71% (41–91%), respectively], or ethanol, methanol and uEtG taken in combination with 73% (45–92%). Specificity of all markers was 92% or higher. Additional testing of hEtG revealed alcohol consumption in seven patients, not being positive for any other marker. Phosphatidylethanol was a highly specific and sensitive marker for detection of recent alcohol consumption in pre‐ and post‐transplant patients. The additional determination of hEtG was useful in disclosing alcohol consumption 3–6 months retrospectively.

Commentary on the Paper of Thompson P. et al.: Phosphatidylethanol in Postmortem Brain and Serum Ethanol at Time of Death.

THE PAPER OF Thompson and colleagues (2016) contributes from both a scientific and a clinical point of view to a timely and relevant issue, namely the potential role of the ethanol (EtOH) metabolite phosphatidylethanol (PEth) as a biomarker for assessing EtOH intake in autopsy cases. To facilitate early diagnosis and therapy of alcohol-related disorders and thus prevent secondary complications, questionnaires like the Alcohol Use Disorders Identification Test (AUDIT) (Saunders et al., 1993) together with reliable and valid biomarkers are useful. Clearly, biomarkers have the advantage to indicate and reflect alcohol intake, independent of recall bias of the interviewed subjects. Among biomarkers of EtOH intake, EtOH metabolites such as ethyl glucuronide (EtG) and, more recently, PEth have been investigated. PEth is now recommended by the German evidenceand consensus-based guideline on alcohol use disorders (AUD) for screening chronic alcohol intake at the highest level of evidence (level 1) in all settings for assessing drinking habits (Mann et al., 2015; Weinmann et al., 2016). PEth has been employed in settings such as the assessment of driving ability, in forensic psychiatry, in monitoring programs, and for identifying alcohol intake in specific risk groups, for example, for neonatal screening of prenatal alcohol exposure (for review, seeWurst et al., 2015). It should be noted that PEth is not a single molecule but a family of phospholipids with different fatty acids at the sn-1 and sn-2 positions (Gnann et al., 2010). Nutrition can influence the lipids available to be transformed into PEth homologues and thus mediate the substitution of different fatty acids. Liquid chromatography tandem mass spectrometry (LCMS/MS) allows PEth to be detected in blood after a single drinking episode, while multiple drinking on 5 subsequent days leads to the accumulation of PEth in blood (Gnann et al., 2012). In volunteers, a single drinking episode to a blood alcohol concentration (BAC) of 1.0 g/kg (approx. 0.1 g/dl) resulted in a detection window of 3 to 12 days (Schr€ ock et al., 2017). During abstinence, the ratios of different PEth homologues change due to their differing elimination times (Gnann et al., 2014). As PEth seems to be formed as long as alcohol is present in the blood, and higher BAC levels lead to a higher formation rate, the manner of drinking (speed, frequency, single-drinking amounts) and the BAC reached per drinking event may play roles in PEth production. However, this has not yet been investigated in detail. No paper has so far looked at PEth degradation in vivo, nor its mechanism of degradation and which products are formed. Apart from phospholipase D (PL D) activity, PL A1, PL A2, PL B, and PL C can also lead to different forms of “lyso”-PEth, which are currently not detected by LC-MS/ MS methods. A variety of possibilities might explain interindividual differences in the formation of certain PEth homologues. The investigated samples were autopsy cases from a brain bank with death by suicide or from natural causes. To establish a diagnosis, the Mini-International Neuropsychiatric Interview (M.I.N.I.) with DSM-IV (American Psychiatric Association, 1994) criteria were employed. Of note, a differentiation between a lifetime and a current diagnosis of AUD was not possible with the given information. This would have been of interest for data interpretation. In addition to this excellent diagnostic tool, it would be beneficial in future studies to have information about EtOH intake over the days, weeks, and months prior to death. Such information could have been provided by the AUDIT or by timeline follow back, as used for many other studies with living persons. The study is based on PEth concentrations, serum blood levels, and coroner’s reports, reports from next of a kin, on the manner of death and circumstances with the differentiation of suicide and death from natural causes, with a relatively small number of autopsy samples, and thus should be regarded as a pilot study. The samples used were classified into 3 groups: AUD-W (with positive serum EtOH levels present at the time of autopsy), AUD-WO (without positive serum EtOH levels), and controls. As the control group was positive for PEth, it From the Institute of Forensic Medicine (WW, AS), University of Bern, Bern, Switzerland; Institute of Forensic Medicine (AS), Kantonsspital Aarau, Aarau, Switzerland; Paracelsus Medical University (FMW), Salzburg, Austria; University of Basel (FMW), Basel, Switzerland; and Center for Interdisciplinary Addiction Research (FMW), University of Hamburg, Hamburg, Germany. Received for publication November 24, 2016; accepted December 19, 2016. Reprint requests: Friedrich M. Wurst, Paracelsus Medical University, Strubergasse 21, 5020 Salzburg, Austria; E-mail: frieder.wurst@gmx.de Copyright© 2017 by the Research Society on Alcoholism.