Y
ou are probably familiar with one of the steps—horizontal gaze nystagmus (HGN)—the involuntary movement
(bouncing) of the eyes. While there may be several factors affecting HGN, alcohol is a primary contributor. An HGN evaluation consists of an evaluator holding his or her finger or an object in front of the person’s nose and asking them to follow it with their eyes as the evaluator moves the object on a horizontal plane from leſt to right across their face. Research has shown a correlation to the angle of HGN onset and a person’s blood alcohol content (BAC).1 Another more familiar tool used to
quantify a person’s BAC is a preliminary breath test (PBT)—oſten referred to as a breathalyzer. A law enforcement officer may use HGN and PBT tests help establish probable cause to determine if someone is under the influence of alcohol. Other estab- lished alcohol testing formats available for identifying current impairment include rapid tests for urine and saliva. Traditional alcohol testing methods are
effective in identifying very recent alcohol consumption and current intoxication, but their short window of detection is not suf- ficient for use in abstinence monitoring, a common requirement in probation, parole, corrections, and drug courts. For example, the drug court model combines both rehabilitative and criminal justice elements that follow the “Ten Key Components” established by the National Association of Drug Court Professionals (NADCP). Te fiſth key component recommends that abstinence be monitored by frequent alcohol and other drug testing and is con- sidered central to the NADCP drug court model. Te traditional alcohol-monitoring method, ethanol testing, has a substantial drawback as drug courts oſten operate within the traditional Monday to Friday work week and lack the ability to effectively monitor participants over the weekend. It is common for drug courts and
probation offices to conduct an increased
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number of drug and alcohol tests on Mon- days in an effort to identify people that are violating their “no drugs and alcohol” re- quirement. While traditional drug screens will generally identify weekend violations of illicit drug use of up to two or three days, it was more difficult to detect alcohol use in the same period of time.2 Ethyl Glucuronide, or EtG, is a unique
biomarker produced by the liver following alcohol use. It was first discovered in human urine in 1967 (Jaakonmaki et al). EtG has since been identified in various bodily fluids, tissues, and hair, thereby providing a variety of testing options.3
Unlike more traditional
alcohol testing that measures the concentra- tion of ethanol, EtG is a direct metabolite of ethanol, which is formed by an enzymatic conjugation of ethanol with glucuronic acid. Te primary advantage of measuring EtG over ethanol is that EtG can be detected in urine for up to four days aſter alcohol con- sumption, compared to only 8–15 hours for ethanol. Ethy Sulfate (EtS) is another more recently identified alcohol metabolite that is used as an indicator of ethanol ingestion. EtS is a direct bio-marker of alcohol ingestion that is not susceptible to degradation by bacteria hydrolysis and is tested in conjunction with EtG for confirmation purposes.4
EtG and
EtS when used together seem to offer slightly greater sensitivity to alcohol use than either biomarker alone.5 In addition, ethanol can be produced
in vitro due to fermentation of urine samples containing sugars (diabetes), bacteria or yeast when samples are exposed to warm temperatures4,7
The primary advantage of
measuring EtG over ethanol is that EtG can be detected in urine for up to four days after
alcohol consumption, compared to only 8–15 hours for ethanol.
In such
cases, an EtG/EtS test can be used as a confirmatory test to determine if the alcohol in the sample is due to consump- tion of alcohol or it is formed in vitro as a result of fermentation. It is also possible to lower the concentration of EtG by drinking large amounts of water prior to voiding, whereas this strategy does not influence the EtG/creatinine ratio or the concentration of urine ethanol.6
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