Letter to the Editor Phosphatidylethanols (PEths) are a group of abnormal phospholipids that can serve as direct alcohol biomarkers. They are formed within the human body from phosphatidylcholines upon enzymatic catalysis by phospholipase D, by exchange of the choline group against ethanol, when alcohol is present. The use of PEths as alcohol biomarker became popular, as they accumulate in red blood cells (RBC), prolonging the window of detection up to several weeks. 1 This can be advantageous for abstinence monitoring when compared with ethyl glucuronide (EtG) and ethyl sulfate (EtS) in urine. 2 Currently,

Phosphatidylethanols (PEth) are a group of abnormal phospholipids which are formed within the human body in the presence of ethanol. As PEth accumulates in red blood cells, which prolongs its detectability, it became popular as a direct alcohol biomarker. When alcohol is consumed regularly, PEth concentrations in the human blood reach an equilibrium (plateau) between formation and degradation which is representative of drinking habits. A wide range of applications has been demonstrated for PEth, whereby in most studies it could provide advancements regarding accuracy and precision when compared to already established alcohol biomarkers (carbohydrate-deficient transferrin, gamma-glutamyltransferase, and ethyl glucuronide). Although PEth has been the focus of many research projects all around the world, the final breakthrough from the research laboratory into the clinical mass market is still ongoing. In this overview article, we discuss the evolution of PEth analysis, its applications, and the associated challenges. The main reasons that hinder the use of PEth in the mass market were identified as (a) the lack of implementing a uniform reference measurement system, which should ensure that every single PEth result is comparable and/or (b) ensuring good laboratory practice dedicated to PEth analysis, which should guarantee that every result obtained by an individual laboratory is correct. These challenges regarding PEth analytics must be carefully addressed in the near future before the implementation of common cut-off values and international guidelines can take place.

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Aims Phosphatidylethanol (PEth) is used to monitor alcohol consumption in alcohol use disorder (AUD). In this study, we aim to evaluate the elimination time of PEth with regard to the clinically established 200 and 20 ng/ml cutoffs for PEth 16:0/18:1. Methods Data from 49 patients undergoing treatment for AUD were evaluated. PEth concentrations were measured at the beginning and repeatedly during the treatment period of up to 12 weeks to monitor the elimination of PEth. We evaluated the time in weeks until the cutoff concentrations of <200 and <20 ng/ml were achieved. The correlation between the initial PEth concentration and the number of days until the PEth concentration had dropped below 200 and 20 ng/ml was assessed by calculating Pearson’s correlation coefficients. Results The initial PEth concentrations ranged from <20 to >2500 ng/ml. In 31 patients, the time until the cutoff values were reached could be documented. Even after 6 weeks of abstinence, PEth concentrations above the cutoff of 200 ng/ml could still be detected in two patients. A strong significant positive correlation was found between the initial PEth concentration and the time required to drop below the two cutoffs. Conclusion A waiting period of more than 6 weeks after declared abstinence should be granted for individuals with AUD before using only one single PEth concentration to assess the consumption behavior. However, we recommend to always use at least two PEth concentrations for the evaluation of alcohol-drinking behaviors in AUD patients.