March 14, 2016 | From the Lab Bench
EtS/EtG vs Ethanol Testing
By Jill Warrington, MD
Burlington Labs Chief Medical Officer
Detection of ethanol metabolites EtG and EtS (Ethyl Glucuronide and Ethyl Sulfate) have largely replaced the traditional method of ethanol testing for assessing alcohol consumption. There are good clinical reasons for this.
In most clinical settings, the combination of EtG/EtS testing is far superior to ethanol testing in that it is both more sensitive (identifies more cases of alcohol ingestion) and is more specific (is less likely to pick up erroneous cases). The increased sensitivity is, in part, due to the fact that the EtG/EtS method lengthens the detection window for alcohol exposure: Ethanol can be detected for only a few hours after consumption, while EtS and EtG can be detected for approximately 24 hours and 80 hours, respectively. Usually clinical assessment alone can detect the alcohol intoxication that can be identified by ethanol testing.
Another reason for the improved sensitivity of the EtG/EtS method is that they are generally stable at warmer temperatures. Ethanol, by contrast, can volatilize at warmer temperatures and be missed in testing. This difference is particularly relevant if samples are shipped at warmer temperatures, collected in warmer climates or during the summer months.
The EtG/EtS method offers improved specificity as well. The presence of EtG or EtS in urine indicates that the ethanol has been processed by the body. Ethanol, on the other hand, can be generated in the presence of sugars and yeast/bacteria by a process of fermentation. By this process, one could erroneously conclude that a patient has consumed alcohol when in fact they have not.
It should be noted that incidental alcohol exposure through hand sanitizer, NyQuil and the like will be seen in all forms of alcohol testing, including EtG/EtS and ethanol.
Any treatment provider who has questions about how to interpret drug-screen or confirmation-test results, or how to order the most helpful test profile for a particular situation, is always welcome to call our lab team for guidance.