AI Summary A PEth (phosphatidylethanol) test is an alcohol biomarker blood test that gives liver doctors an objective result alongside what you share about drinking. It is compared here with EtG, GGT, and MCV. Doctors may order it to support stopping alcohol, during a liver evaluation, or when transplant is considered. A result shows alcohol exposure, not liver damage, so your care team reads it with your history and other tests. Talk with your doctor before quitting if you drink heavily.
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PEth is short for phosphatidylethanol. It is one of the alcohol biomarker tests that liver doctors use to learn whether alcohol is a factor in a person's liver health.
A result is one piece of information. Your care team uses it to support you, not to judge you.
Below, you will find key facts, how PEth fits with other alcohol markers, why doctors order it, what to expect, and answers to common questions.
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About the test
PEth stands for phosphatidylethanol. A PEth test is an alcohol biomarker test. An alcohol biomarker is a substance measured in the body that helps show whether a person has been drinking.
Doctors sort alcohol markers into two groups. Direct markers come from the way the body processes alcohol itself. Indirect markers, such as the liver enzyme GGT and the red blood cell measure MCV, show how alcohol may be affecting the body. They are less specific to alcohol. Ethyl glucuronide (EtG), one direct marker, is considered superior to GGT and MCV.
These tests matter in alcohol-related liver disease (ARLD), also called alcohol-associated liver disease. The first step in treating it is to stop drinking all alcohol. A biomarker test can support that goal by adding an objective lab result to what you tell your care team.
For the full group of markers, see Alcohol Biomarker Testing. For treatment options, see Alcohol-Related Liver Disease Treatment.
Alcohol biomarker comparison
Different markers answer different questions. Your care team chooses the mix that suits your situation.
| Marker | Type | What to know |
|---|---|---|
| PEth | Alcohol biomarker blood test | Ask your lab or care team how far back your result looks and how it is read. |
| Urine EtG | Direct marker | Detects alcohol use for up to 80 hours. Cirrhosis does not influence it. |
| Hair EtG | Direct marker | Tracks drinking for up to six months. Each 1 cm segment reflects about one month. |
| GGT and MCV | Indirect markers | Show how alcohol may be affecting the body. Less specific to alcohol. |
See also the CDT and EtG guides linked above.
Why it is ordered
In alcohol-related liver disease, the first step in treatment is to stop drinking all alcohol. Early fatty liver from alcohol will usually reverse on its own if drinking stops. A biomarker result can show your care team how recovery is going.
When a doctor suspects alcohol-related liver disease, they ask about your drinking and arrange blood tests to check how your liver works. Imaging, a liver biopsy, or an endoscopy may follow if the disease looks advanced.
People with cirrhosis who keep drinking are not eligible for a liver transplant. Objective results can be part of the conversation between you and your transplant team.
Blood test and results
PEth is measured in a blood sample, so you give a sample at a clinic or lab. Your care team will tell you whether you need to prepare in any way. Follow their instructions, because collection rules can differ between labs.
A PEth result shows alcohol exposure, and it does not tell your doctor how much liver damage you have. Your care team reads it together with your history, your liver blood tests, and imaging. Ask how your lab reports results and what the numbers mean for you, since reference points vary.
No single test is perfect. A result that does not match your experience is worth discussing openly. Your doctor may repeat the test or add another marker, such as [CDT](/liver-tests/alcohol-drug-toxicology-testing/alcohol-biomarker-testing/cdt) or [urine EtG](/liver-tests/urine-stool-testing/specialized-urine-testing/alcohol-biomarker-urine-test).
After your result
Whatever your result shows, support is available. If you drink heavily, do not stop suddenly on your own. Quitting "cold turkey" may not be safe, and severe withdrawal can be life-threatening. Talk with your doctor first. Call your doctor right away if you have severe withdrawal symptoms, and seek emergency care for confusion, seizures, or hallucinations.
A balanced, liver-friendly diet supports your liver, helps manage weight and blood sugar, and lowers the risk of other health problems during long-term follow-up.
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Common Questions
PEth stands for phosphatidylethanol. It is an alcohol biomarker blood test. That means it measures a substance in the body that helps show whether a person has been drinking. Liver doctors can use it to learn whether alcohol is a factor in a person's liver health. Your care team reads the result together with your history and your other tests.
No, it is not a liver function test. A liver function test checks how well your liver is working. A PEth test looks for a sign of alcohol exposure, not for damage to the liver. Doctors pair it with liver blood tests and imaging to get a fuller picture of your liver health.
Your lab and care team can tell you. This page does not give a PEth detection window. For comparison, urinary EtG can detect alcohol use for up to 80 hours, and EtG in scalp hair can track drinking for up to six months. Do not apply those numbers to PEth. Ask your lab how far back your result looks.
Not on its own. A direct marker is more specific to alcohol than GGT or MCV, but it shows alcohol exposure, not how much liver damage you have. When a doctor suspects alcohol-related liver disease, they ask about your drinking and arrange blood tests. Imaging, a liver biopsy, or an endoscopy may follow if the disease looks advanced. Your doctor reads any PEth result with your history and these other tests.
Talk with your doctor before you stop if you drink heavily. Quitting suddenly may not be safe, and severe withdrawal can be life-threatening. A doctor can help you find an approach that is right for you. Medicine, counseling, and support groups, especially together, help many people quit. Depending on your liver function, medicine may not be an option. When drinking stops, the liver can shed built-up fat and repair itself, and it is never too late to quit.
Medical disclaimer: LiverDirectory provides educational information and a directory of providers. It does not provide medical advice, diagnosis, or treatment. Always consult a licensed physician regarding any medical condition.
