What is PEth (Phosphatidylethanol)?
PEth (Phosphatidylethanol) is a specific alcohol biomarker. It provides the highest sensitivity for the detection of current, regular alcohol consumption. It is particularly effective for detecting chronic and heavy drinking.
Who uses PEth testing?
PEth testing is useful when you need to show the level of alcohol consumption in the previous month. PEth enables monitoring of individuals with known alcohol use issues, such as child protection cases and drink driving violations.
What are the advantages of PEth testing?
Phosphatidylethanol (PEth) which only forms in the presence of ethanol is a direct marker for alcohol intake.
This makes PEth a more sensitive indicator than existing blood markers of CDT, LFT and FBC. Changes in CDT, LFT and FBC can be caused by other health issues, making them less specific alcohol use.
Is a PEth test better than a hair alcohol (EtG) test?
PEth and hair testing for alcohol each have their advantages and disadvantages. PEth is eliminated from the body in about 28 days, meaning the window of detection is often given as one month. However, hair EtG testing can provide information regarding alcohol use over the past three months.
Often, both a hair and blood are collected at the same time. The results complement each other. The two timeframes enable a comparison between recent and long-term alcohol use.
What sample is used for PEth testing?
A small sample of blood is collected via a finger prick using a compact device that pierces the skin. Droplets of blood are collected into a specially designed kit and then transferred to a filter paper card which is allowed to dry before being securely packaged. This sample is referred to as a dried blood spot.
How much blood is required for a PEth test?
Only five or six drops of blood are required for a PEth alcohol test.
Are PEth samples secure and stable for transport?
The collected sample is a dried blood spot. Because the blood is dried out, it does not require refrigeration or special storage. The sample is stable through collection, transport and storage.
Is PEth quantitative? What are the test levels of PEth?
PEth testing is quantitative, meaning the amount or quantity of PEth can be established. The PEth homologue 16:0/18:1, the most common homologue tested for, is analysed at Cansford Laboratories. PEth test levels are expressed as ng of PEth per mL of blood.
PEth <20 ng/mL:
Abstinence or irregular low alcohol consumption in the approximate month prior to the sample collection.
PEth between 20 – 200 ng/mL:
Consistent with alcohol consumption, but not at an excessive level, in the approximate month prior to the sample collection.
PEth >200 ng/mL:
Excessive alcohol consumption in the approximate month prior to the sample collection.
How long does it take for PEth to leave the body?
It can take a number of weeks following abstinence from alcohol for all PEth to be eliminated. This will depend on the original PEth level that the individual had.
For example, if a PEth level was high five to six weeks prior to sample collection and then a person stopped drinking alcohol, the PEth level detected in the sample may be higher than the expected for the amount of alcohol consumed within the past four weeks.
What can affect PEth levels?
The level of PEth can be affected by a number of factors, such as differences in metabolism and frequency of alcohol consumption. The consumption of a higher number of drinks on one occasion will produce a higher blood alcohol concentration and consequently a higher PEth result than if the same number of drinks were consumed on five separate occasions.
Can PEth test detect occasional drinking?
Irregular, low alcohol consumption is less likely to show up on a PEth test as <20 ng/mL.
It is important to note however, that a “not detected” result doesn’t necessarily mean that the PEth is 0 ng/mL. The cut off <20 ng/mL accounts for the small amounts of alcohol naturally produced by the body.
Occasional high consumption, such as binge drinking, may result in a high PEth level.
What is the PEth test detection time?
PEth can be detected for approximately 28 days after alcohol use. This means a PEth test will go back as far as one month for most individuals.
Sometimes it can take more than four weeks following abstinence from alcohol for all PEth to be eliminated. This will depend on the original PEth level that an individual had.
Can PEth test results be interpreted?
Depending on the level found, PEth test results can be interpreted as:
- abstinence or irregular low alcohol consumption;
- consistent with alcohol consumption but not at an excessive level; and,
- excessive alcohol consumption.
See the above question Is PEth testing quantitative? What are the test levels of PEth?
If required, a more detailed interpretation of the PEth result can be obtained via the purchase of an expert report.
