Ethyl Glucuronide Testing

What is Ethyl Glucuronide?  Ethyl Glucuronide (EtG) is a minor, non-oxidative metabolite of ethanol.  EtG is non-volatile, water soluble, and relatively stable during storage.  Presence of EtG in urine or other specimens is strong forensic evidence of recent alcohol consumption.

Why test for EtG?   EtG is a biomarker that indicates recent alcohol use.  EtG testing is best suited to individuals who are involved in zero-tolerance or compliance monitoring programs.  EtG has two distinct advantages over traditional ethanol testing: The first being that EtG may be detectable in urine for up to 80 hours* post ethanol consumption.  Urine ethanol testing provides a post-alcoholic beverage consumption detection window of 1-12 hours.  The second advantage EtG testing has over ethanol testing is ethyl glucuronide is less prone to degradation during prolonged storage.  Urine ethanol samples require special handling to prevent rapid ethyl alcohol degradation.  In addition, clinically significant levels of ethanol can be develop in glucose and yeast-positive urine and cause false-positive results.  The formation of exogenous EtG post-sample collection is a possibility (Helander et al, 2007), but unlikely to be clinically significant at higher cut-off levels.                   

 *Detection window for EtG will depend on frequency and amount of ethanol consumed

Is EtG testing reliable?  We are aware of only one medication that may potentially cause false-positive results when using immunoassay screening for EtG; there are no known false-positives or interference when using LC/MS/MS to confirm presumptive positive screening results.  A confirmed positive EtG test is proof of recent alcohol consumption.  There are some anecdotal reports of EtG positive results occuring due to "innocent" exposure to ethanol through alcohol-containing personal care products and OTC cold remedies.  In most of these studies, positive EtG test results were obtained when these products were used in amounts that far exceeded normal and practical application.  To minimize the possibility of "innocent" positive results, Options Labs recommends using a cut-off of 500 ng/ml.  A lower cut-off can be used with zero tolerance programs and cases where a client's access to alcohol-containing products is restricted.

Can EtG results be used as a tool to measure impairment?  A positive EtG result means that alcohol has been consumed and processed by the liver.    EtG production is dependent on several variables (liver enzyme activity, sex, amount of alcohol consumed, time interval since last drink) and therefore, the quantitated amount of EtG present in a urine sample cannot be directly tied to a specific amount of alcohol consumed.   In general, the higher the amount of EtG in a sample, the heavier and/or more recent the alcohol consumption has been.

Sample Handling?  Urine samples for EtG testing do not require any special handling.  Etg is stable in urine at room temperature for up to four days (exposure to heat has been shown to increase stability of EtG), so samples do not need to be frozen if received by Options Lab up to four day post-collection.  In a study conducted by Helander et al (2007), E. coli bacteria present in urine was shown to slowly degrade EtG over time.  E. coli bacteria will be present in the urine of an individual with a urinary tract infection and could be introduced to the urine sample by accidental contamination.  Under these conditions, a sample not tested within four days could have a false negative result.

For more information on EtG testing, please contact Options Lab, Inc. at 920-882-1646