PEth Alcohol Testing

A phosphatidylethanol (PEth) test is a type of blood alcohol test that looks for the presence of PEth, an abnormal phospholipid and direct biomarker of alcohol, in a blood sample.

PEth requires ethanol (the intoxicating agent in alcoholic drinks) for its production, meaning that it is only present in the body when alcohol has been consumed, providing the most conclusive insight into a person’s drinking patterns.

When combined with other blood alcohol tests such as Carbohydrate Deficient Transferrin (CDT) testing, Mean Corpuscular Volume (MCV) testing, or a Liver Function Test (LFT), a thorough bank of evidence can be collated regarding an individual’s alcohol use.

PEth is also the only form of blood alcohol testing that is recommended to be performed during pregnancy or within two months of birth.

Although PEth is the most conclusive of the blood alcohol tests, a more in-depth insight can be drawn by considering the results of all tests side-by-side.

This is especially important where the safeguarding of children and vulnerable people is paramount, enabling family law professionals and authorities to act on urgent welfare needs.

Learn more: Blood alcohol testing methods

Drinking experiments show that Phosphatidylethanol (PEth) can be detected in blood after 1-2 hours and for up to 4 weeks prior to sample collection. It is so sensitive that it can be detected for up to 12 days after just a single drinking episode.

Additionally, daily alcohol consumption of more than 60g of ethanol can be clearly distinguished from lower alcohol consumption.

This means that PEth testing can detect chronic and single-drinking episodes. It can also be used to monitor abstinence, drinking behaviour, identify relapse, and verify whether an individual has changed their pattern of alcohol consumption.

We can also provide repeat PEth testing over several months for ongoing monitoring, if required.

The table below shows the range of PEth levels that can be measured using an AlphaBiolabs’ blood alcohol PEth test.

For family law cases where the safeguarding of children is paramount, PEth alcohol testing is a valuable tool for monitoring a parent or caregivers’ ability to care for a child.

PEth is a direct biomarker of alcohol, meaning it can only be found in the body when ethanol – the intoxicating agent in alcohol drinks – is consumed. This makes it the most accurate and reliable of all the blood alcohol tests available for family court proceedings.

PEth can be detected in the blood within 1-2 hours of alcohol consumption and can also detect alcohol misuse in the 4 weeks prior to blood sample collection.

The test is so sensitive that it can also be used to detect single drinking episodes up to 12 days after alcohol was consumed.

The wealth of information provided by a PEth test, alongside its conclusiveness, is what makes it the most essential of all blood alcohol tests.

Repeat PEth testing (e.g. monthly) allows the court to monitor patterns of use over time, assess compliance with court orders and identify relapse or recovery.

This is especially valuable when contact or custody arrangements are under review, as it offers a clearer, more consistent evidential picture to support decisions that prioritise child welfare.

Family law solicitors, social workers, local authority employees and private individuals who require PEth testing for a legal or official matter can instruct us for a court-approved PEth test.

If you are a legal professional, social worker, or local authority employee looking for court-approved PEth alcohol testing to support you client’s case, call 0333 600 1300, email testing@alphabiolabs.com or complete our online quote form.

If you are a private individual looking for court-approved PEth alcohol testing for a private legal or official matter, call 0333 600 1300, email info@alphabiolabs.com or visit this page to request a call back from our expert team.

Phosphatidylethanol (PEth) is a direct biomarker of alcohol, meaning that PEth is only present in the body when ethanol (the intoxicating agent in alcoholic drinks) has been consumed.

PEth production begins in the body as soon as ethanol is consumed and accumulates in the blood with frequent alcohol use, giving it a high specificity (48-89 per cent) and sensitivity (88-100 per cent).

High levels of alcohol consumption results in higher concentrations of PEth, while low alcohol consumption leads to lower concentrations.

Drinking experiments show that PEth can be detected in the blood after 1-2 hours and for up to 4 weeks prior to sample collection. It is so sensitive that it can be detected for up to 12 days after just a single drinking episode.

Additionally, daily consumption of more than 60g of ethanol (the intoxicating agent in alcoholic drinks) can clearly be distinguished from lower alcohol consumption.

PEth can be detected in the blood after 1-2 hours and for up to 4 weeks prior to sample collection.

It is so sensitive that it can be detected for up to 12 days after just a single drinking episode.

Yes, PEth testing can be used to detect a single drinking episode for up to 12 days after alcohol consumption.

Unlike other laboratories that require a venous blood draw for PEth alcohol testing, an AlphaBiolabs PEth test simply requires a few blood drops which are collected using a finger prick device.

This is more cost-efficient for customers, with no phlebotomy or venepuncture skills required to perform the blood sample collection. It is also ideal for Sample Donors who are needle phobic or have poor vein access.

PEth is a direct biomarker of alcohol, meaning it is only present in the body when alcohol has been consumed.

This makes PEth alcohol testing the most accurate of all the blood alcohol tests available for family court proceedings.

PEth can be detected in the blood after 1-2 hours and for up to 4 weeks prior to blood sample collection. Even a single drinking episode can be detected for up to 12 days after alcohol was consumed.

The sensitivity of PEth alcohol testing makes it ideally suited for child welfare and safeguarding cases, allowing the court to monitor patterns of use over time, assess compliance with court orders and identify relapse or recovery (abstinence).

We pride ourselves on offering some of the fastest results in the UK for court-approved alcohol testing, within 3-5 business days of receipt of samples at our laboratory.

Our expert team of in-house toxicologists can also expedite PEth alcohol test results to meet urgent court deadlines. 

To request a quote for PEth alcohol testing, call us on 0333 600 1300, email testing@alphabiolabs.com or complete our online quote form, and a member of our team will contact you to discuss your requirements.

The results of a PEth alcohol test will show the PEth levels that were present in the blood at the time the sample was collected.

PEth accumulates in the blood with more frequent alcohol consumption, making it possible to determine whether a person has remained abstinent, consumed alcohol in small/moderate amounts, or whether there has been excessive drinking in the four weeks prior to the blood sample being drawn.

The below table shows the range of PEth levels that can be measured using an AlphaBiolabs PEth blood alcohol test:

At AlphaBiolabs, our standard report for legally-instructed PEth alcohol tests is the Expert Report – the most comprehensive report available, and the one most relied upon in family court proceedings.

An Expert Report sets out expert interpretation in full, and is the document that gives family courts, solicitors, social workers and local authorities the most complete picture of what the results mean.

It includes the full analytical findings alongside the professional conclusions of the Reporting Scientist, contextualised by donor disclosures, relevant scientific caveats, metabolite analysis, and any other factors material to the case.

For cases where the results are likely to be contested, where the science is complex, or where the outcome could significantly affect a child’s future, our Expert Report ensures the findings are properly understood and appropriately applied.

All AlphaBiolabs test reports are produced to be legally defensible, are accepted in every UK family court, and are also peer-reviewed by a senior Reporting Scientist before issue.

PEth is a direct biomarker of alcohol, meaning it is only produced in the body when ethanol has been consumed.

Unlike indirect biomarkers such as CDT, LFT and MCV, which can be elevated by medical conditions, medications or other factors unrelated to alcohol, PEth cannot be produced by the body through any mechanism other than alcohol consumption.

This makes false positives extremely unlikely. A positive PEth result is strong evidence that alcohol has been consumed in the period prior to sample collection.

As with all scientific testing, results should always be interpreted by a qualified expert in the context of the individual case, alongside any other relevant evidence.

We offer four types of blood alcohol test at AlphaBiolabs that can be called upon for evidence in court.

PEth is the most conclusive of all the blood alcohol tests, as PEth is a direct biomarker of alcohol that is only present in the blood when alcohol has been consumed.

However, performing PEth alcohol testing alongside other blood alcohol tests can provide an even more thorough insight into an individual’s alcohol use.  

Other blood alcohol tests we offer at AlphaBiolabs include:

• Carbohydrate Deficient Transferrin (CDT) test

  CDT is an indirect marker of alcohol. A minimum of two weeks’ sustained alcohol use is needed to increase CDT above cut-off levels. However, it usually returns to normal levels within four weeks after drinking ends.

  Detection window: up to 1 month overview

• Liver Function Test (LFT) – also known as a liver blood test, this test is used to assess the functionality of the liver. It’s performed by checking the levels of certain enzymes and proteins in the blood.

  Detection window: snapshot of liver function at the time of the test

• Mean Corpuscular Volume (MCV) test – an MCV test is used to measure the average size of red blood cells. These cells carry oxygen around the body, supporting the function of tissues and organs.

  Detection window: approximately 4 months

It’s worth noting that, unlike PEth testing, CDT, LFT and MCV tests can be impacted by medical conditions unrelated to alcohol use and should therefore be considered alongside other evidence when interpreting results.

Learn more: PEth vs. other tests

PEth is second only to the detection of ethyl glucuronide (EtG) and ethyl palmitate (EtPa), a fatty acid ethyl ester (FAEE), in the hair.

Both EtG and EtPa are biomarkers of alcohol and give us a highly accurate insight into patterns of drinking, with a three- or six-month overview of usage (whereas the PEth result provides a detection period of up to 4 weeks prior to collection).

EtG and EtPa are absorbed into the hair via different routes, and their levels can assist in assessing excessive alcohol consumption.

EtG is water soluble, produced in the liver and can be impacted by various hair treatments including excessive washing.

EtPa is formed in the sebaceous glands from ethanol diffusing from the blood circulation and then deposited into hair primarily from sebum (from the oil glands on the scalp). EtPa (FAEE) is lipophilic so while not water soluble, its presence can be affected using alcohol-containing hair products such as sprays, gels, and wax.

Because of their respective strengths and weaknesses, both EtG and EtPa tests should be performed together, and their findings used to support each other, as shown in LB Richmond v B & W & B & CB [2010] EWHC (2903) Fam, where Mr Justice Moylan gave guidance on the evidential worth of hair strand testing.

Within this guidance, it was also stressed that hair strand tests/hair alcohol tests should not be used in isolation to reach evidential conclusions.

By performing these tests in conjunction with PEth and other blood tests, a more holistic conclusion can be drawn as to a person’s alcohol use.

PEth is the only form of blood alcohol testing that is recommended during pregnancy or within two months of birth.

The test is non-invasive, with only a small finger prick blood sample required, and carries no risk to mother or baby.

Other blood alcohol tests such as Carbohydrate Deficient Transferrin (CDT) testing, Liver Function Testing (LFT) and Mean Corpuscular Volume (MCV) testing can be affected by pre-existing medical conditions, medications, and the physiological changes that typically occur during pregnancy (such as increased blood volume and changes to liver function).

PEth is a direct biomarker of alcohol, meaning it is only detectable in the blood when alcohol has been consumed, and is unaffected by pregnancy-related physiological changes.

Yes, PEth testing can be used to demonstrate abstinence or chronic & excessive alcohol consumption.

While PEth is the most conclusive blood alcohol test available, combining it with CDT, LFT and MCV testing can provide a more complete picture of an individual’s alcohol use, which can be particularly valuable in family law proceedings where the safeguarding of children and vulnerable people is a priority.

Each test has a different detection window and measures alcohol use in a different way. Used together, they can corroborate or contextualise each other’s findings, giving legal professionals, social workers and courts a stronger evidential basis on which to act.

For example, an elevated MCV result, which reflects changes to red blood cells over approximately four months, combined with a high PEth result indicating excessive alcohol consumption in the past month, paints a more compelling picture of sustained heavy drinking than either test would alone.

It is also worth noting that CDT, LFT and MCV are indirect biomarkers of alcohol, meaning their results can be influenced by factors unrelated to alcohol use. Where these tests return elevated results alongside a positive PEth result – a direct biomarker unaffected by such factors – the case for alcohol misuse is strengthened significantly.

For the most comprehensive overview of an individual’s alcohol use, our Comprehensive Alcohol Analysis package combines head hair alcohol testing with all four blood alcohol tests (PEth, CDT, LFT and MCV) and includes an Expert Report and sample collection.

To request a quote, call us on 0333 600 1300, email testing@alphabiolabs.com or complete our online quote form, and a member of our team will contact you to discuss your requirements.

Yes. While PEth testing is widely used in family law proceedings, including child welfare cases, custody disputes and care proceedings, it can also be used in a range of other legal and personal contexts.

These include:

• Personal injury and employment tribunal cases, where evidence of alcohol use may be relevant
• Driving offences, where an individual may need to demonstrate abstinence or changed drinking behaviour to the DVLA or a court
• Private individuals, who may wish to obtain a PEth test to support a personal legal or official matter

AlphaBiolabs’ Expert Reports are legally defensible and accepted in every UK family court, making them suitable for use across a wide range of legal settings.