EtG Test for Confirming Alcohol Abstinence

Applications, Cutoff Values, Limitations, and Accuracy

Is Urine Testing Effective?
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The ethyl glucuronide (EtG) test is widely used to detect the presence in urine of ethyl glucuronide, a breakdown product of ethanol, the intoxicating agent in alcohol. It can also screen for EtG in your blood, hair, and nails, but the urine test is the most widely used. The main purpose of an EtG test is to document​ required alcohol abstinence.

What It's Used For

The test for EtG is widely used to detect alcohol abstinence in situations that do not allow drinking, including:

  • Alcohol treatment programs
  • A DUI or DWI program
  • Liver transplant patients
  • Schools or the military
  • Professional monitoring programs (for example, airline pilots, healthcare 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.

Detection Timeframe

You may be surprised to learn that after consuming alcohol only about 0.5 percent to 1.5 percent of it is eliminated in your urine. That's after it undergoes a process called glucuronidation to form the breakdown product EtG. 

The EtG test is quite sensitive and can detect even low levels of alcohol. In fact, the test can detect alcohol in the urine up to five days after consumption.

In studies of participants without alcohol-use disorders, EtG has been detected in urine samples for up to 80 hours (3.3 days) after heavy alcohol exposure.

Limitations

A problem with the EtG test is that it can produce a positive test from the mere exposure to alcohol that's 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

The reality is that there are hundreds of household products that contain ethanol, according to the National Library of Health's Household Products Database, and exposure to them could possibly lead to a false positive on the EtG test.

Interpreting Results

The Substance Abuse and Mental Health Services Administration (SAMHSA) has suggested the following cutoff values:

"High" positive EtG test (for example, >1,000ng/mL) may indicate:

  • Heavy drinking on the same day or the 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:

  • Heavy drinking within the last one to three days
  • Light drinking within the last 12 to 36 hours
  • Recent exposure to environmental products containing alcohol

SAMHSA lists EtG as a test that can help both rule in or rule out whether someone has been drinking with high accuracy.

For instance, as what's called a "sensitive" test, the EtG test accurately detects a person who recently consumed alcohol 70 percent or more of the time. One study showed that for moderate to heavy drinking, this number jumps to 85 percent.

As a "specific" test, the EtG test identifies people who did not recently consume alcohol 70 percent or more of the time—and up to 89 percent of the time if they weren't drinking moderately to heavily.

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 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. 

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