Urine tested positive for ethyl glucuronide after trace amounts of ethanol

Ethyl glucuronide (EtG) is used commonly as a marker for the detection of non-compliance of patients in alcohol withdrawal therapy in psychiatric hospitals in Europe and in work-place monitoring programmes in the United States. With the increased use of this new marker, questions related to an unintentional uptake of ethanol resulting in detectable EtG concentrations have been discussed. The aim of this study was to determine the concentration ranges of EtG and ethyl sulphate (EtS) after the consumption of very small amounts of ethanol (1 and 3 g), which are more likely to be incidental than intended.

Drinking experiments with ethanol amounts of 1 and 3 g, respectively, were performed on a total of 31 volunteers. EtG and EtS analysis in urine was performed by electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS), and creatinine concentration was determined using the Jaffé reaction. Furthermore, data obtained from this experimentation were then compared to data from literature.

The maximum concentration of EtG normalized to creatinine after the uptake of 1 g and 3 g of ethanol was found to be 0.32 mg/l and 1.53 mg/l, respectively, and 0.15 mg/l and 1.17 mg/l for EtS; these peak concentrations are considered to be positive by many laboratories testing urine for ethanol conjugates in work-place testing progammes.