Etg And Peth: Fda-Approved Alcohol Biomarkers?

Ethyl glucuronide (EtG) and phosphatidylethanol (PEth) are two of the most sensitive alcohol biomarkers available. They are used to monitor alcohol abstinence in individuals mandated to abstain, and to detect alcohol consumption. EtG can be detected in various body fluids, tissues, and hair, while PEth is a blood biomarker. Both can be measured in the same blood sample, providing valuable information on recent alcohol consumption. While EtG is the preferred analyte for detecting alcohol consumption, PEth has promising clinical applications. The combined use of PEth and EtG is supported, and they are used as complementary biomarkers for alcohol consumption.

Ethyl glucuronide (EtG) and phosphatidylethanol (PEth) are the most sensitive alcohol biomarkers

Alcohol biomarkers are used to monitor both recent and long-term drinking and provide information about drinking habits as a complement to self-reporting. Ethyl glucuronide (EtG) and phosphatidylethanol (PEth) are the most sensitive available biomarkers for this purpose.

EtG and PEth concentrations seem to be independent. Their combined measurement in the same blood sample is possible and will provide valuable information regarding recent alcohol consumption complementary to self-reporting.

A study examined 1000 forensic reports of participants enrolled in a professionals health program who were contractually obligated to abstain from alcohol and who underwent recovery status evaluations. Out of 52 evaluations in which urinary EtG, EtS, and blood PEth were measured, PEth, at a cutoff concentration of 20 ng/mL, revealed alcohol use more frequently than EtG or EtS.

Another study collected data on both PEth and EtG in the same blood sample, in addition to ethanol, in order to evaluate the combined use of these biomarkers. Of the 1149 samples, 95 were positive for ethanol (range 0.11–3.12 g/L), 454 for EtG (1.0–9739 ng/mL), 635 for PEth (0.014–6.0 µmol/L), 534 for PEth ≥ 0.050 µmol/L, and 315 for PEth ≥ 0.30 µmol/L.

PEth is more likely to be positive in those with alcohol use disorders (AUD)

Alcohol use disorder (AUD) is a chronic disease with significant medical, social, and psychological implications. It is the most common substance use disorder in the United States, with 29.5 million people 12 and older affected. AUD is characterised by a loss of control and progression to addiction.

Phosphatidylethanol (PEth) is a biomarker used to detect unhealthy alcohol consumption. It is one of the most sensitive biomarkers available for this purpose, alongside ethyl glucuronide (EtG). PEth can be quantified in dried blood spots (DBS) and is correlated with alcohol consumption, with higher concentrations indicating more severe alcohol use.

PEth is particularly useful for detecting alcohol consumption over the past three weeks. Studies have shown that PEth concentrations are significantly higher in individuals with an alcohol disorder diagnosis compared to those without. In one study, 45.8% of patients had a PEth concentration of ≥ 0.03 μmol/L, indicating significant alcohol consumption. This was further supported by a positive correlation between PEth concentrations and Alcohol Use Disorders Identification Test (AUDIT) scores, which are used to identify unhealthy drinking behaviours.

The PEth 16:0/18:1 homologue is the most abundant in human blood and is often quantified for clinical and forensic purposes. Research suggests that PEth 16:0/18:1 analysis can help distinguish between abstinence or light drinking and moderate or unhealthy drinking due to the correlation with consumption and PEth levels.

In summary, PEth is a valuable tool for detecting unhealthy alcohol consumption and is particularly likely to be positive in individuals with AUD. It provides complementary information to self-reporting and other biomarkers, contributing to a more comprehensive understanding of an individual's drinking habits.

EtG is more likely to be positive in those without AUD

The EtG test is a widely used method to detect the presence of ethyl glucuronide in urine, blood, hair, and nails. It is a highly sensitive biomarker of alcohol consumption that can detect low levels of alcohol ingestion. This sensitivity can lead to false positives, as EtG tests can react to exposure to alcohol in many daily use products. This includes household items, which could trigger a positive result in someone who has not consumed alcohol.

The test is most often used to ensure abstinence from alcohol, as it can detect alcohol consumption in the days leading up to the test. EtG is eliminated from the body over time, particularly by drinking water and other fluids. However, drinking water is not a reliable method to manipulate test results, as laboratories can detect tampering with urine samples.

EtG tests are not recommended for workplace testing programs as they do not measure current impairment from alcohol. The test is also not suitable for situations where individuals are suspected of impairment while driving or at work, as it measures previous alcohol consumption.

The test is considered very useful for detecting recent alcohol consumption, but it is advised to use a combination of alcohol biomarkers for confirmation. A positive EtG test usually confirms exposure to ethanol in the days before the test. However, a negative test shows that a person was not exposed to ethanol within the testing time frame of up to five days.

The sensitivity of the test means that it can be triggered by exposure to alcohol in daily use products, which are often used by people without AUD. This means that a person without AUD is more likely to trigger a positive EtG test result, as they are more likely to be exposed to these products. For example, a person with AUD may be abstinent from alcohol but could still trigger a positive result due to exposure to environmental alcohol. Therefore, the EtG test is more likely to be positive in those without AUD due to its sensitivity and reactivity to environmental factors.

EtG can be detected in various body fluids, tissue and hair

Ethyl glucuronide (EtG) is a direct metabolite of ethanol. It is formed in the body as long as ethanol is present, during the non-oxidative metabolism of ethanol by conjugation with activated glucuronic acid. EtG is a very sensitive biomarker of alcohol consumption. It can be detected in various body fluids, tissues, and hair.

EtG can be detected in body fluids such as whole blood, serum/plasma, cerebrospinal fluid, and urine. It is detected in body fluids even when there is no alcohol left in the body, indicating that ethanol has recently been consumed. EtG can be detected in blood for about 36 hours and for several days in urine and tissues following the cessation of alcohol intake. Consumption of a relatively small quantity of alcohol may result in a detectable EtG level in urine for up to 6 hours. Detection time is longer after the consumption of higher amounts of alcohol. EtG can also be detected in sweat and breath.

EtG is also present in body tissues such as the liver, fat, brain, vitreous humor, and bone marrow. The liver showed the highest concentration of EtG, with up to 77 μg g−1 tissue. Bone marrow, which is often still available in cases of extensive decomposition, could be a useful tissue when other specimens are unavailable.

EtG can be detected in hair, which provides the best retrospective detection compared to other matrices. Hair is relatively non-invasively collected, is difficult to adulterate, and can be a promising marker for post-mortem investigations of alcohol use. EtG was detected in the hair of a socially acceptable alcohol user at autopsy, with a concentration of 14 ng mg−1.

Biomarker results are more accurate when PEth and EtG are used together

Phosphatidylethanol (PEth) and ethyl glucuronide (EtG) are both direct and specific biomarkers of alcohol. This means they are only created when ethanol is metabolized or reacts with substances in the body. In other words, they can only be detected when alcohol has been consumed.

PEth is the most accurate of the blood tests to determine alcohol abuse. Its high specificity (48–89%) and sensitivity of 88–100% is because it is directly related to alcohol consumption. However, EtG is superior to PEth when it comes to hair alcohol testing. EtG can become trapped within the keratin fibres along the length of a nail, providing a detection period of up to 12 months.

Although PEth and EtG concentrations seem to be independent, their combined measurement in the same blood sample is possible. This provides valuable information regarding recent alcohol consumption that complements self-reporting. When used together, these biomarkers can monitor both recent and long-term drinking and provide information about drinking habits.

In a study of 1149 venous EDTA blood samples, 95 were positive for ethanol, 454 for EtG, 635 for PEth, 534 for PEth ≥ 0.050 µmol/L, and 315 for PEth ≥ 0.30 µmol/L. Another study of 519 blood samples found that PEth was the single most positive biomarker (64%), and the only positive chronic biomarker in 100 cases.

In summary, PEth and EtG are highly effective biomarkers for alcohol consumption, and when used together, they provide complementary information that improves the accuracy of results.

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