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USDTL Research

Made In The Blood

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PEth testing in dried blood spot specimens offers legal and addiction treatment professionals the highest degree of sensitivity and reliability of any alcohol biomarker.

by Joseph Salerno

Blue surgical gloved hand holding a whole blood test.

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Alcohol abuse is a significant health and economic concern in the United States today. Almost 17 million people can be categorized as having an alcohol use disorder. Alcohol use is the third leading preventable cause of death, accounting for more than 88,000 alcohol related deaths each year. In 2012, alcohol-impaired driving was the cause of 10,322 driving fatalities. In the United States, alcohol abuse accounts for more than $223 billion in annual economic costs. More than 50% of child custody cases involve alcohol and drug abuse as a factor for judges to consider.

There are several measures of alcohol use to help healthcare, addiction treatment, and legal professionals evaluate their clients’ alcohol use issues. The measurement of the objective ethanol biomarker phosphatidylethanol (PEth) in blood samples offers the most unbiased, sensitive, and reliable method for evaluating alcohol use.

Self-report of alcohol use has several limitations due to social stigma, self-incrimination, and recall bias. Indirect biomarker testing (CDT, GGT, and MCV) measures the biological effects of alcohol consumption on the body – not alcohol consumption itself – and can be confounded by several factors such as age, cancer, changes in liver function, infection, and pregnancy.

Other direct alcohol biomarkers can even be problematic. Urine is a very easily adulterated testing sample, and testing for ethyl glucuronide/sulfate (EtG/EtS) in urine provides a very short window of detection (1-3 days). EtG testing in hair samples, although far superior to urine testing and indirect biomarkers, can be dramatically affected by the use of cosmetic hair treatments such as dyes, straighteners, and bleaching.  Additionally, a sufficient hair specimen – 1.5 inches in length from the scalp – is not always available.

PEth testing in blood does not suffer from any of these issues. PEth is an abnormal phospholipid molecule that is created and captured in red blood cell membranes. The more often a person consumes alcohol, the more PEth is accumulated in the resevoir of the cell membrane.

Blood is a universal specimen that is always available. The collection of blood samples is an observed collection, making adulteration impossible. Despite being a blood sample, PEth testing does not require a blood draw, but can instead be accomplished using dried blood spots from a finger stick.

Dried blood spot collection is simple, quick, and is accomplished by the donor under observation by a collection professional (after a brief training session). The donor pricks their finger using a lancet (similar to those used in diabetic testing) and then deposits the blood drops on a filter paper card. This avoids the expense of a phlebotomist and can be accomplished in a non-clinical setting. Blood spot cards are compact and very simple to ship.

Laboratory professionals are able to extract the blood drops from the cards and test them for PEth levels. Capturing the blood spots on the filter cards fixes the cells at the moment they were collected, and prevents any further degradation or production of PEth, eliminating any possible change in the testing result.

PEth testing is able to detect binge alcohol consumption in the 2-3 weeks prior to collection of the sample. The window of detection is far superior to that of urine testing. The simplicity of collection makes repeat testing during long-term monitoring simple and minimally invasive, both physically and in terms of a donor’s time.

Several studies have demonstrated that PEth is unaffected by age, race, gender, disease states, changes in liver function, infection, or pregnancy, in contrast with indirect alcohol biomarkers. PEth testing has also been shown to improve alcohol use self-report in a number of studies.

PEth testing has been used successfully in several counties in the State of Wisconsin to reduce drunk-driving recidivism and lower costs associated with 12-month driver’s safety plans following DUI convictions. Other outpatient treatment programs have associated PEth testing with a reduction in patient relapse rates.


1. Viel, G., Boscolo-Berto, R., Cecchetto, G., Fais, P., Nalesso, A., and Ferrara, S.D. (2012). Phosphatidylethanol in blood as a marker of chronic alcohol use: A systematic review and meta-analysis. International Journal of Molecular Sciences, 13, 14788-14815.

2. Bean, P., Brown, G. and Lewis, D. (2012). Direct alcohol biomarkers as tools to guide meaningful intervention while monitoring recent repeat intoxicated drivers in Kenosha County. Research Society on Alcoholism National Conference. Poster Presentation. San Francisco, CA.

3. Helander, A., Peter, O. and Zheng, Y. (2012). Monitoring of alcohol biomarkers PEth, CDT and EtG/EtS in an outpatient treatment setting. Alcohol and Alcoholism, 47(5), 552-557.

4. Hahn, J.A., Dobkin, L.M., Mayanja, B., Emenyonu, N.I., Kigozi, I., Shiboski, S. and Wurst, F.M. (2012). Phosphatidylethanol (PEth) as a biomarker of alcoholism consumption in HIV-positive patients in sub-Saharan Africa. Alcoholism Clinical and Experimental Research, 36(5), 854-862.

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