68 Phosphatidylethanol: Detecting Alcohol in General Population and Transplant Patients

Alcohol consumption can lead to serious health consequences, including motor impairments and organ failure. Testing for short-term alcohol use is routinely conducted using blood ethanol tests in clinical laboratories. Gamma-glutamyl transferase (GGT), although nonspecific, has traditionally been used to indicate liver disease and can also serve as an indirect marker of alcohol use. When it comes to identifying heavy alcohol users—particularly among patients being evaluated for organ transplants, there is an urgent need for more reliable biomarkers. More recently, phosphatidyl ethanol (PEth), a group of abnormal phospholipids formed in cell membranes due to alcohol consumption, has gained prominence for its greater sensitivity and specificity in detecting heavy alcohol use. PEth has been traditionally analyzed in whole blood with liquid chromatography-tandem mass spectrometry (LC-MS/MS) as two isomers: 18:1 (fatty acid:double bond) and 18:2 (fatty acid:double bond). Although PEth is an ideal marker for alcohol due to its high sensitivity, specificity, long half-life, and direct formation from ethanol, few studies have compared its alcohol detection efficacy to other markers especially for transplant patients (primarily liver transplant patients). We compared ethanol, GGT, and PEth testing results over three years in both the general and transplant populations within our hospital system. The positive rates for each marker were analyzed to assess alcohol use patterns, with a particular focus on transplant patients’ adherence to pre- and post-surgery abstinence. Among the three markers, PEth more accurately identifies chronic alcohol use than ethanol and GGT (flagged positive rate: 28% PEth, 19% ethanol and 48% GGT) in both the overall and transplant populations. In addition, PEth 18:1 and PEth 18:2 were compared to determine whether PEth 18:2 offers additional value beyond PEth 18:1. All samples that tested positive for PEth 18:2 also had positive PEth 18:1 results, but the reverse was not always true, indicating that PEth 18:1 is a more sensitive marker of alcohol use. While PEth 18:1 and PEth 18:2 showed a fair correlation, no fixed percentage ratio was observed between them. These findings suggest that PEth 18:1 alone may be sufficient for reliably detecting alcohol consumption.