Monitoring of the Alcohol Biomarkers PEth, CDT and EtG/EtS in an Outpatient Treatment Setting

Aims: To compare the sensitivity of whole blood phosphatidylethanol (PEth) with serum carbohydrate-deficient transferrin (CDT) as biomarkers of current regular alcohol consumption, during outpatient treatment for alcohol-related problems. Urinary ethyl glucuronide (EtG) and ethyl sulfate (EtS), and clinical assessment, were used as complementary estimates of relapse to drinking. Methods: Biomarker results for 29 men and 11 women (aged 20-73 years) undergoing voluntary outpatient treatment for harmful alcohol use or dependence were utilized for this evaluation. In connection with visits to the unit, blood and/or urine were sampled for measurement of PEth, EtG and EtS (by liquid chromatography-mass spectrometry), and CDT (%disialotransferrin, by high-pressure liquid chromatography). Results: The comparison included 326 whole blood, 319 serum (1-82 samples/patient) and 654 urine samples (1-178 samples/patient) collected over similar to 2 years. At the initial assessment, the total PEth value ranged between 0 and 16.5 mu mol/l (mean 2.6) with 70% being above the quantification limit (0.1 mu mol/l) and 55% above the reference interval (0.7 mu mol/l). Initial CDT values were 0.87-6.9% (mean 2.1) with 35% above the applied reference interval (1.7%). At the final sampling (treatment period up to 21 months), the total PEth value had decreased to 0-5.9 mu mol/l (mean 0.6; P = 0.0004) and CDT to 0.87-3.3% (mean 1.3; P = 0.0030). Relapses were detected by PEth alone (43% of cases), by PEth and CDT (38%) and the remainder by EtG/EtS. Conclusion: PEth was the most sensitive biomarker of current regular alcohol consumption. PEth-16:0/18:1, usually being the major subform, was as sensitive as total PEth. PEth, CDT and EtG/EtS are useful complementary tools for objective identification of current drinking and relapse detection.