The PEth value is an alcohol marker in the blood that reflects consumption over roughly the last 2 to 4 weeks. According to the assessment criteria (Beurteilungskriterien), a value below 20 ng/ml counts as abstinence, 20 to 200 ng/ml indicates relevant consumption and above 200 ng/ml excessive consumption. PEth has been recognised for the MPU (medical-psychological assessment, Medizinisch-Psychologische Untersuchung) since the 4th edition of the assessment criteria (2022).
What is PEth in the first place?
PEth stands for phosphatidylethanol and is a direct alcohol marker that is measured in the blood. It is regarded as a marker of the amount of alcohol consumed and shows whether, and to what extent, alcohol was drunk in the past weeks.
Unlike the classic liver values such as GGT, GOT, GPT, MCV or CDT, PEth is not an indirect indication but a direct marker. Today, liver values hardly play a role any more for proof of abstinence (Abstinenznachweis) and can only show "good values" as a supplement. PEth, on the other hand, is increasingly becoming the standard.
Since when has PEth been recognised for the MPU?
PEth has been recognised for the MPU since the 4th edition of the assessment criteria (2022). The assessment criteria ("Urteilsbildung in der Fahreignungsbegutachtung", forming judgements in fitness-to-drive assessment) are the professional standard according to which assessors evaluate.
Since then, PEth can be used as a supplement or an alternative to EtG. The 5th edition of 2026 currently applies. How proof of abstinence is structured overall is explained on the page Proof of abstinence.
For you, this recognition above all means more flexibility: alongside urine and hair tests, PEth offers a further way to prove abstinence. Which combination makes sense depends on your case and your programme.
What period does the PEth value cover?
The PEth value reflects alcohol consumption over roughly the last 2 to 4 weeks. In terms of time, it therefore lies between EtG in urine, which only goes back a few days, and EtG in hair, which covers around 3 months.
This makes PEth a useful component: a single blood sample says more about the past weeks than a single urine sample, but is independent of hair length and hair treatment.
How are PEth values classified?
PEth values are classified into three ranges: below 20 ng/ml counts as abstinence (decision limit of the assessment criteria, 4th edition), 20 to 200 ng/ml as relevant consumption and above 200 ng/ml as excessive consumption. The unit ng/ml is equivalent to µg/l.
| PEth value | Classification (guideline) | Meaning for proof of abstinence |
|---|---|---|
| below 20 ng/ml | Abstinence | consistent with proof of abstinence |
| 20–200 ng/ml | Relevant consumption | not proof of abstinence |
| above 200 ng/ml | Excessive consumption | not proof of abstinence, indication of considerable consumption |
Since the 4th edition of the assessment criteria, the limit of 20 ng/ml has applied uniformly to all laboratories. How your result is assessed in the individual case is decided by the assessment centre (Begutachtungsstelle für Fahreignung).
Why lab values and the interview must fit together
In the psychological interview, the assessor checks the consistency between the case file, the questionnaire, lab values and your account. Contradictions are noticed immediately. A PEth result is therefore not just formal proof, but part of your credibility: it should match what you say about your current behaviour.
How does PEth differ from EtG?
PEth and EtG are both direct alcohol markers, but they differ in the type of sample and the time window. Which marker makes sense for you depends on your programme and your living circumstances.
| Marker | Sample | Time window (guideline) | Special feature |
|---|---|---|---|
| EtG in urine | Urine | approx. 24–80 hours | unannounced appointments, sample usually to be given within ~24 hours |
| EtG in hair | Hair | approx. 3 months (max. 3 cm per analysis) | unusable with dyed or bleached hair |
| PEth | Blood | approx. 2–4 weeks | independent of hair treatment, as a supplement or alternative |
When PEth is particularly useful
PEth is particularly useful if a hair analysis is not an option. This is the case, for example, if you dye, bleach or tint your hair, because the EtG hair analysis is then unusable. The details are explained in the guide Hair analysis for the MPU.
PEth can also help to build a coherent overall picture as a supplement to EtG tests. Whether and how PEth is used in your programme is determined by your laboratory and the programme.
What requirements apply to PEth proof?
PEth proof only counts for the MPU if it meets the same formal requirements as other proof of abstinence. The CTU criteria (chemical-toxicological testing, Chemisch-Toxikologische Untersuchung) are decisive.
- Accredited laboratory under DIN EN ISO/IEC 17025 (forensic toxicology).
- Recognition by the assessment centre: ask beforehand whether the programme is accepted.
- Identity check and complete documentation of the sample chain (chain of custody).
- Continuous programme over the required period, usually 6 or 12 months.
- Bring all results in the original to the MPU.
Can PEth also play a role with controlled drinking?
In principle, PEth can also be relevant if controlled drinking rather than abstinence is an option for you, because the marker reflects the amounts drunk. However, controlled drinking is only possible if there is no finding of dependence and you are living a plausible, permanently stable concept.
In cases of dependence, advanced misuse, repeat offences or very high per mille values (rule of thumb: above about 2.0‰), only abstinence has a prospect of success. Which route fits your case file is explained on the page MPU because of alcohol.
What does a raised PEth value mean for your programme?
A value above the abstinence guideline can invalidate an ongoing abstinence programme, so that the abstinence clock usually starts again. That costs time, but it is not the end of the road.
What matters is dealing with it honestly. A concealed relapse that comes to light later costs you credibility in the psychological interview. It is better to understand the cause and restart properly. Also bear in mind that EtG, for example, can also test positive because of food containing alcohol or mouthwash, so avoid such products if in doubt.
What you can do now
- Clarify through file inspection (Akteneinsicht) whether, and for how long, you have to prove abstinence.
- Ask your laboratory whether PEth is included in your programme, as a supplement or instead of hair analysis.
- Pay attention to the formal requirements: accredited laboratory, recognised programme, complete documentation.
- Keep all PEth results in the original and bring them to the MPU.
- If you want to prepare for the interview at the same time: find suitable preparation.
Frequently asked questions
Which PEth value counts as abstinent?
According to the assessment criteria, a PEth value below 20 ng/ml (µg/l) counts as abstinence. Values between 20 and 200 ng/ml indicate relevant consumption, values above 200 ng/ml excessive consumption.
How far back does a PEth test go?
About 2 to 4 weeks. It therefore covers more than EtG in urine, but less than EtG in hair.
Can I use PEth instead of a hair analysis?
Yes, PEth is an alternative, for example if you have dyed or bleached hair. Whether your programme provides for this is something you clarify with your laboratory.
Are liver values not just as meaningful?
No. Liver values such as GGT or CDT are only indirect markers and hardly play a role any more for proof of abstinence. PEth and EtG are direct alcohol markers.
