LC-MS/MS of PEth in whole blood: implementation in routine clinical chemistry

In clinical practice, assessing alcohol intake can be challenging because patients may under-report or misjudge their consumption, so biomarkers of chronic intake provide valuable additional information. Phosphatidylethanol (PEth) is a group of abnormal phospholipids that are formed in cell membranes only in the presence of ethanol (alcohol). We developed, analytically validated, and clinically implemented a rapid and robust LC-MS/MS-based method for quantifying PEth (16:0/18:1) in whole blood. The method demonstrates a limit of detection (LOD) of 0.01 μM and a limit of quantification (LOQ) of 0.03 μM, with confirmed linearity up to at least 0.8 μM. Validation using reference materials and samples from patients with liver disease and self-reported alcohol intake confirmed its accuracy. Clinical implementation over a two-month period, involving 20 analytical batches, demonstrated inter-assay precision below 15%. Our results support the clinical applicability of PEth use for accurate estimation of alcohol intake in humans.