How long can a PEth test detect alcohol?

How long can a phosphatidylethanol (PEth) test detect alcohol? Well, drinking experiments have shown that PEth can be detected in blood after 1–2 hours following a single drinking episode. This PEth detection can also last for up to 12 days.

Because PEth is a direct biomarker of alcohol, it is the most accurate blood test to determine alcohol abuse.

Its production begins as soon as ethanol is consumed and PEth peaks within 8 h after alcohol ingestion. Once formed, it degrades very slowly, which is important for its use as an alcohol biomarker.

The quantity of alcohol consumed affects PEth in a fairly straightforward manner. High levels of alcohol consumption produce high concentrations of PEth. Low alcohol consumption leads to low PEth concentrations.

Another advantage of PEth is that it can clearly distinguish daily alcohol consumption of more than 60 g ethanol from lower alcohol consumption. One unit of alcohol is defined as 8 g of pure alcohol. As a comparison, AlphaBiolabs’ other blood alcohol tests of carbohydrate‐deficient transferrin (CDT), mean corpuscular volume (MCV) and liver function tests (LFT) generally require the daily consumption of over 60 g/day of alcohol over several weeks to cause clinically significant elevations. This means that PEth testing can detect chronic as well as single-drinking episodes.

The table below shows the range of PEth levels that can be measured in AlphaBiolabs’ blood alcohol testing.

PEth level < 10 µg/L Abstinence or very low alcohol consumption in the past month.
PEth level 10–35 µg/L Low/occasional alcohol consumption in the past month.
PEth level 35–210 µg/L Social/moderate alcohol consumption in the past month.
PEth level > 210 µg/L Excessive alcohol consumption in the past month.


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