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Phosphatidylethanols (PEth) are a group of phospholipids formed only in the presence of ethanol via the action of phospholipase D. Levels of phosphatidylethanols in blood are used as markers of previous alcohol consumption. For this purpose, PEth is more sensitive than carbohydrate deficient transferrin (CDT), urinary ethyl glucuronide (EtG) and ethyl sulfate (EtS).
Intake of less than 48 g ethanol/day for three weeks gives a whole blood a PEth concentration of <0.7 μmol/l. Repeated ethanol intake of 48–102 g per day for three weeks gives a blood PEth of 1.0–2.1 μmol/l. After cessation of alcohol intake, the half-life of PEth is between 4.5 and 10 days in the first week and between 5 and 12 days in the second week.
Chemically, phosphatidylethanols are phospholipids carrying two fatty acid chains, which are variable in structure, and one phosphate ethyl ester.