Widely-Used EtG Test for Confirming Alcohol Abstinence

Is Urine Testing Effective?
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A widely-used urine test, the EtG (Ethyl Glucuronide) test, is a biomarker test that detects the presence of ethyl glucuronide (a breakdown product of ethanol) in urine samples. It can also detect the presence of EtG in blood, hair, and nails, although the urine test is the most widely used. 

The purpose of an EtG test is used to document alcohol abstinence, but it can only measure recent alcohol intake, within the last one to three days.

Interpreting the EtG Urine Test

You may be surprised to learn that after consuming alcohol, only about 0.5 to 1.5 percent of it is eliminated in the urine, and this is after undergoing a process called glucuronidation to form the breakdown product, EtG. 

Even so, the EtG test is quite sensitive and can detect even low-levels of alcohol. In fact, the test can technically detect alcohol in the urine up to five days after consumption. That said, in studies of participants who are not alcoholics, EtG has been detected in urine samples for up to 80 hours after heavy alcohol exposure, so up to three days is probably a more reasonable estimate.

Due to the common use of EtG to confirm recent alcohol abstinence, the 2012 Substance Abuse and Mental Health Services Administration (SAMHSA) has suggested the following cutoff values, based on scientific research:

"High" Positive EtG Test (for example, >1,000ng/mL) May Indicate:

  • Heavy drinking on the same day or previous day 
  • Light drinking on the same day as the test

"Low" Positive EtG Test (for example, 500 to 1,000ng/mL) May Indicate:

  • Heavy drinking within the last one to three days
  • Light drinking within the last 24 hours
  • Recent intense exposure to environmental products containing alcohol (within the last 24 hours)

    "Very Low" Positive EtG Test (for example, 100 to 500 ng/mL) May Indicate:

    • Previous heavy drinking within the last one to three days
    • Previous light drinking within the last 12 to 36 hours
    • Recent exposure to environmental products containing  alcohol

    A problem with the EtG test is that it can produce a positive test from the mere exposure to alcohol that is present in many daily use products. Examples of environmental or home products that contain alcohol include:

    • Foods prepared with or flavored with alcohol
    • Cleaning products
    • Mouthwashes
    • Breath sprays
    • Hand sanitizers
    • Hygiene products like antiperspirant
    • Aftershave
    • Cosmetics
    • Hair dye

    In fact, there are hundreds of household products that contain ethanol, according to the National Library of Health's Household Products Database, and this could possibly lead to a false positive on the EtG urine test.

    Also, gender, age, or ethnicity may also affect EtG test results, but more research is needed to tease this out. Even so, according to the 2012 SAMHSA Advisory, it's believed that gender, age, and ethnicity probably do not affect the results of EtG.

    In addition, the SAMHSA lists EtG as a "highly" sensitive and specific alcohol biomarker. As a sensitive test, this means that EtG test accurately (at least 70 percent or more of the time) detects a person who recently consumed alcohol.

    As a specific test, this means that the EtG accurately (at least 70 percent or more of the time) identifies people who did not recently consume alcohol. 

    Application of the EtG Test

    The test for EtG is widely used to detect alcohol abstinence in situations that do not allow drinking. Examples include:

    • Alcohol treatment programs
    • A DUI or DWI program
    • Liver transplant patients
    • Schools or the military
    • Professional monitoring programs (for example, airline pilots, health care professionals, attorneys)
    • Court cases (for example, child custody)
    • Probation programs

    It's important to note that the EtG test is not recommended for use in workplace testing programs, as it does not measure current impairment from alcohol.

    A Word From Verywell

    All in all, the EtG test is considered a highly useful test for detecting recent alcohol consumption. But like any test, there is the possibility for a false positive. This is is why a "positive test" should be confirmed either with another test or with verification from the person that he or she did indeed drink alcohol. 

    Hopefully, as the research on EtG and other alcohol biomarkers unfolds, a clearer cutoff value can be made in order to distinguish between true alcohol use and exposure to alcohol in environmental products. 

    Sources:

    Jatlow, P., & O’Malley, S. S. (2010). Clinical nonforensic application of ethyl glucuronide measurement: Are we ready? Alcoholism: Clinical and Experimental Research, 34(6), 968–975.

    National Drug Screening. (2017). EtG Alcohol Test.

    Substance Abuse and Mental Health Services Administration. (2012). The Role of Biomarkers in the Treatment of Alcohol Use Disorders, 2012 Revision

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