A term, "innocent positve" is being used to identify a positive EtG test that was not the result of beverage alcohol use but was truly an accidental incidental exposure.
A problem with defining incidental exposure is that items that could be presumed to be sources of incidental exposure (e.g. vanilla extract, tincture of gingko biloba, cepacol mouthwash, nyquil, to name a few) if taken on purpose or in excessive amounts stretch the definition of incidental exposure beyond credibility. Additionally, if someone violates a signed abstinence agreement, by knowingly consuming food with alcohol, or by using using any prohibited substance, and the prohibition of use of these substances was in the signed agreement, again this would go beyond the common sense definition of incidental exposure.
Incidental exposure would be defined as unintentional or accidental exposure. Incidental then implies lack of intention.
False positive technically refers to a test that reports positive when the substance was not actually present. Sometimes this term is also used clinically to describe a positive test from a person who tested positive but shouldn't have because of some other explanation other than direct intentional use of the substance.
Cutoff is the number which if exceeded in the sample tested causes a positive report to be made. The cutoff level is set sometimes for more than one reason including technical reasons (that the lab technique cannot reliably go below the number) and clinical reasons (if we only want to detect higher values) usually to minimize the number of people detected and select those that have less potential of positives from non-beverage alcohol.
EtG Advisory - August 15, 2005
(Download Advisory in Letter format: pdf)
The following updated advisory has been developed in response to questions from monitoring programs and regulatory boards regarding EtG testing:
- No laboratory test is 100% accurate. Clinical correlation is always important.
- Some people produce more EtG for a given dose of ethanol than others associated with a known genetic polymorphism in the human UDP-glucuronyl transferase enzyme system. The exact limits of this variation are not known.
- A positive EtG is not proof of intentional alcoholic beverage consumption. Low level positive tests are known to occur due to incidental exposure. The cutoff for possible incidental exposure vs intentional use has not been accurately established, due to many factors including; amount of "incidental" exposure, individual metabolism, hydration, kidney function, etc..
For the above reasons it is advisable, whenever possible, to refrain from taking action against an employee or licensee based on urine EtG testing alone. In the presence of a positive EtG test, if alcohol use is denied, we encourage the use of clinical evaluation by an addiction medicine specialist to more fully assess the meaning of a positive test. We encourage Boards, Courts, and/or Employers to rely on Addiction Medicine assessments to help interpret positive test results.
Despite the above limitation many monitoring programs have found EtG testing to be useful for early detection of alcohol use. EtG is a far superior marker for recent alcohol use than previous tests. More investigation is currently underway.
Questions and Answers:
-Have you heard credible reports from around the country that have caused you to question the 100% reliability of the test? We never presumed or meant to suggest that EtG testing is 100% reliable. We feel very confident that the only reason for EtG in urine is to have had ethanol in the body, however, the extent and effect of incidental exposure in all subjects has not been fully explored or defined.
-Is it your recommendation that EtG testing results not be relied upon carte blanche at this point. Yes.
-Do you believe that until further study can be done, any score under 1000 could be questioned legitimately. These are rough guidelines. I would encourage clinical correlation, especially when the level is below 1000, the patient denies drinking, and there is no other evidence of problems. I would not advise taking action against a licensee if the only evidence of a problem is a low positive EtG test.
-Will EtG testing results stand up in court. There are already cases where it has "stood up" in court. In every case that I know about where it has been upheld as meaningful in court or administrative hearings there has also been other information along with EtG testing to compel a decision. I would be hesitant to rely on a low level EtG test by itself.
INTERPRETING A POSITIVE EtG TEST
As far as is know the sole origin for the presence of EtG in urine is ethanol in vivo, and the only ways for significant ethanol to be present in the body are: 1. Drink an alcoholic beverage, 2. Consume "incidental" alcohol (alcohol in food, normal use of hygiene products, OTC meds, etc), and, theoretically, 3. Produce ethanol endogenously ("auto brewery syndrome"). A positive EtG is common after #1, rare and weakly positive after #2, and not yet proven after #3.
The situation with regards to EtG and "incidental" exposure is similar to that of poppy seeds causing a positive morphine/codeine in urine. "Incidental" exposure for ethanol, however, is limited to products used according to manufacturer recommendations. In other words, drinking a cup of mouthwash is not incidental exposure, but swishing and spitting mouthwash up to 3-4 times per day may be incidental exposure. The concept of "incidental" exposure is also questionable if an agreement has been signed to refrain from using the product for which incidental exposure is claimed.
If auto-brewery syndrome is suspected consider the following protocol. (r/o Auto-brewery protocol (pdf)).
We are attempting to identify numbers and characteristics of cases in which individuals believe they have tested positive in the absence of alcohol beverage consumption. Please go to <registry>* and enter pertinent information. There will be information to download there to assist such individuals in knowing how to proceed and to potentially participate in a study.
Use of Ethylglucuronide Testing
When there is a need to monitor indviduals who have agreed to remain abstinent from alcohol (such as recovering airline pilots, physicians, federal workers in safety sensitive jobs, truck drivers, etc.) who have had problems with alcohol abuse or dependence a biological marker that can accurately detect alcohol use is needed. The ideal test would need to detect alcohol use for up to several days or so prior to testing (high sensitivity). Additionally the test should only be positive following recent alcohol use (high specificity).
Until recently no satisfactory test has been available to meet these criteria. In the absence of a better marker urine alcohol has been used. Unfortunately urine alcohol testing falls short for two reasons. 1. the testing window for detection with urine alcohol is a matter of hours rather than days (poor sensitivity) and 2. fermentation, that produces alcohol, can occur "in-vitro" during shipment or storage of the sample prior to testing (poor specificity). Therefore urine alcohol testing has a significant tendency to produce unreliable results with both false negative and false positive reports.
Ethylglucuronide, EtG, is a new marker that is now commercially available and seems to be ideal when there is a "binary" need to know whether someone has recently been drinking alcohol or not. It is only positive in urine when alcohol is consumed (and combines with glucuronide in the liver).
An important new tool for abstinence testing in monitoring programs
(Ways EtG testing is being utilized)
- Routine inclusion in some or all of sample testing for individuals in monitoring
- "For cause" testing (reports of possible drinking, AOB, etc)
- Random testing in high risk individuals (following multiple relapses, etc)
What is Ethylglucuronide (EtG)
- A direct metabolite of alcohol (accounts for a very small, but important, percentage of alcohol metabolism)
- A stable compound detectable in the urine, blood, hair and post-mortem tissue for days
- More definitive, regarding actual use of alcohol, than indirect measures (i.e. MCV, CDT, GGT, etc).
- Superior to urine alcohol because it is detectable in the urine longer and therefore has a longer time spectrum of detection (2-5 days)
- To test whether or not alcohol has been recently consumed (only useful in testing individuals who should not be drinking at all) - It is not a test for current impairment
- There is essentially no ethylglucuronide present in the urine unless alcohol has been present in vivo. There are virtually no false positive tests, however, an important issue is that must be considered is that there is much non-beverage alcohol in our environment (alcohol as a solvent (in OTC meds), in foods (i.e. vanilla extract), use in rituals (communion wine), etc.) Se FAQ for discussion of cutoffs.
- LC/MS/MS (liquid chromatography/ tandem mass spectroscopy) is currently used to detect ethylgluronide and is highly accurate
- Ethylglucuronide is proving to be particularly useful in numerous settings associated with monitoring individuals committed to abstinence: 1. professionals (such as physicians, pilots, nurses, attorneys, etc) who have had problems with alcohol abuse and have been allowed to return to work based on an abstinence agreement, 2. methadone clinics, 3. individuals with hepatitis C, 4. in legal settings (custody, etc). and 5. in school testing programs, and 6. to confirm other testing methods (i.e. eye testing and sleep testing detection methods)
EtG Discussion Group
This egroup was developed as a forum to discuss EtG testing, benefits, risks, sensitivity, specificity, pros, and cons, and so forth.