"But I didn't drink!": What to do with discordant phosphatidylethanol results

Liver transplantation (LT) teams must be adept at detecting, evaluating, and treating patients' alcohol use, given its prominence among psychological and behavioral phenomena which cause and contribute to liver diseases. Phosphatidylethanol (PEth) is a highly useful alcohol biomarker increasingly recommended for routine use in hepatology and LT. PEth is unique among alcohol biomarkers because of its wide detection window, high sensitivity and specificity, and the correlation of its numerical value with different patterns of alcohol use. Alongside myriad clinical opportunities in hepatology and LT, PEth also confers numerous challenges: little guidance exists about its clinical use; fearing loss of LT access and the reactions of their clinicians and families, candidates and recipients are incentivized to conceal their alcohol use; and liver clinicians report lack of expertise diagnosing and treating substance-related challenges. Discordance between patient self-reported alcohol use and toxicology is yet another common and particularly difficult circumstance. This article discusses the general toxicological properties of PEth; explores possible scenarios of concordance and discordance among PEth results, patient history, and self-reported drinking; and provides detailed clinical communication strategies to explore discordance with liver patients, a key aspect of its use.