What is a urine ethanol test?


What is a urine ethanol test?


Testing alcohol in the body can be done by a few different ways using blood, saliva, breath, sweat, and urine. Of the above ways, blood is considered the gold standard for alcohol testing. Basically, if there is alcohol in your blood stream, it is affecting your body. While blood is the gold standard, it is difficult to test in a workplace setting. To test this way would require a venous blood draw by a qualified person and the blood sample shipped to a lab to be tested. Issues can arise such as a difficult blood draw, improper storage of the sample, and delays in shipping that destroy or otherwise compromise the sample to name a few. The biggest reason for not using blood for alcohol testing is a human rights issue as it is considered a very invasive test, and there are much easier tests that can, by the use of standard tables, be related back to blood alcohol levels. Breath alcohol testing is by far the most common way of testing for the presence and level of alcohol is a person. It is widely used in workplace and law enforcement, and has been tried in the court of law and considered accurate and defensible. Another common way (though much less common than the previous two) to test for the presence of alcohol in the body is testing the urine for the presence of an ethanol biomarker.

The technical name of the test is an “Alcohol Ethanol Glucuronide (EGT) Urine Test”. EGT is a direct metabolite of alcohol that has a long urinary elimination time and is used to detect recent alcohol ingestion even after the alcohol itself is no longer detectable. When alcohol is ingested into the body, it goes through 4 phases. These phases are absorption (happens up to 60 minutes after ingestion), distribution, metabolism, and elimination. With urine EGT testing we are basically concerned with the elimination phase. To eliminate ethanol, the body processes the alcohol through the liver, breaking it down into its metabolite, one of which is EGT (this is the metabolism phase), and is stored in the bladder until it is out of the body (elimination phase). The body can only metabolize a certain amount of alcohol at a time, the average for the population is 0.015 mL/hr, so it can take hours for the alcohol to be metabolized and go to the bladder.

An EGT test will not have a positive result from alcohol until a minimum of an hour, and will continue to be positive for about 80 hours until all of the EGT has passed out of the bladder where it is being stored. Because of the long elimination time it is difficult to relate urine EGT levels back to blood concentration to determine if a person is actually impaired by the alcohol. Accuracy can be improved if a timed two void collection is performed. This is done by obtaining a sample, then timing until a second sample is collected, and sending both samples for testing. They can then do calculations to determine the elimination rate for that individual person and work back to determine if there is any left in the blood. This does improve the accuracy, but is still difficult to give an accurate level in the blood from a legal standpoint. Another downside to this two void process is it is very time-consuming to perform. The other issue with performing urine EGT test is that it is susceptible to adulteration, much like urine drug testing is.

Because of the long detection time in urine, EGT testing it is useful for individuals in rehabilitation programs and in the criminal justice system to confirm that the individual is abstaining from the use of alcohol.

In workplace testing, urine EGT testing can be used for pre-employment testing, but with alcohol being a legal substance, would be difficult to legally eliminate someone from employment with the knowledge that they have consumed alcohol within the last 80 hours before the test. It is not recommended for post incident or reasonable cause testing as it does not link easily to blood alcohol levels so it is hard to determine if the individual is under the influence, or impaired by alcohol, at the time of the incident, or during work time.

The last point to be made about urine EGT testing is that it does not give an instant result as the sample needs to be tested at the lab. This means that at best, it will be a 24-hour turnaround time, and could potentially take a few days depending on shipping times and lab throughput of the test. Compare this to breath alcohol testing that is an instant test and can be easily linked to blood alcohol levels.

Yes, urine EGT testing is still used in workplace settings, but is much less frequent than 15 to 20 years ago, and will likely continue to decrease in popularity due to the many disadvantages of this method of testing.

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Written by John Hawes
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John Hawes is the CCO and co-founder at SureHire Occupational Health Testing. John graduated in 2001 from the University of Alberta with a Bachelor of Science degree in physical therapy. As a former physical therapist, John uses his knowledge of physical therapy and interest in ergonomics and biomechanics to devise fit for work testing.   Full Bio