Why biological markers?
Assessment of alcohol consumption cannot rest solely on the patient's declaration. Not out of distrust — but because subjective perception is often out of step with reality. Biomarkers provide an objective complement, useful both to the doctor and to the patient.
Three markers are mainly used. Each has its indications, its strengths and its limits.
PEth (Phosphatidylethanol)
PEth is a blood marker specific to alcohol consumption. It is formed in red blood cells in the presence of ethanol — therefore only when alcohol is actually consumed. This makes it one of the most specific markers available today.
- Detection window: approximately 2 to 3 weeks.
- Sensitivity: very high — detects moderate and regular consumption.
- Specificity: excellent — few false positives.
- Main indications: initial assessment, follow-up of abstinence or reduced consumption, medico-legal contexts.
CDT (Carbohydrate-Deficient Transferrin)
CDT is a particular form of transferrin, the protein that transports iron in the blood. Chronic alcohol consumption disturbs its structure and makes it detectable.
- Detection window: approximately 2 to 4 weeks.
- Sensitivity: lower than PEth — detects mainly significant chronic consumption (60 g of pure alcohol per day for several weeks).
- Main indications: follow-up of chronic consumption, driving licence recovery contexts, reassuring medical follow-up.
Gamma-GT (GGT) and transaminases
These hepatic enzymes are routinely prescribed in biological check-ups. They may rise in case of chronic alcohol consumption — but also for many other reasons (medications, liver diseases, overweight, viral infections).
- Specificity: low — many other possible causes.
- Usefulness: useful complement in overall follow-up, in association with PEth and CDT.
How are these markers used at the centre?
Dr Sqalli prescribes the markers adapted to your situation and interprets them in consultation, taking into account your complete medical context. The aim is not to judge, but to objectify in order to better support.
Need help interpreting your results?
If you have already received PEth, CDT or Gamma-GT results and wish to discuss them with a specialist physician, book a consultation.