How this instrument works
Ethyl glucuronide (EtG) is a minor metabolite the body produces directly from alcohol, and it can be detected in urine well after alcohol itself has cleared — often for several days after drinking. That sensitivity is exactly why interpreting an EtG result is not as simple as a yes/no cutoff: a low positive result can reflect anything from recent heavy drinking to incidental exposure to alcohol in mouthwash, hand sanitizer, or certain foods and medications, and the result alone can't distinguish between those explanations.
SAMHSA's 2012 advisory sets four interpretive bands rather than one cutoff. Below 100 ng/mL is consistent with abstinence. 100 to 500 ng/mL is a 'very low positive,' which SAMHSA associates with possible heavy drinking one to three days prior, light drinking roughly 12 to 36 hours prior, or incidental exposure to alcohol-containing products. 500 to 1000 ng/mL is a 'low positive,' which SAMHSA associates with previous heavy drinking one to three days prior, recent light drinking in roughly the past 24 hours, or recent intense incidental exposure within about 24 hours — the same kind of ambiguity as the band below it, just at a higher level. Above 1000 ng/mL is a 'high positive,' associated with heavy drinking on the day of the test or the day or two before, or lighter drinking that same day.
This calculator only sorts a number into a band — it does not decide what caused that number or what should happen next. SAMHSA's advisory is explicit that a single EtG result should never be used alone as the sole basis for a punitive decision, such as an employment consequence, probation violation, or treatment program sanction. The bands are deliberately written to acknowledge multiple possible causes rather than a single confirmed conclusion, and any decision with real consequences should involve the full clinical or program context, not this number in isolation.
- Enter the urine EtG level in ng/mL as reported by the lab.
- Read the interpretation band: negative, very low positive, low positive, or high positive.
- Treat the band as one piece of context, not a standalone verdict — see the explanation of what that band can and can't tell you.
Worked example — reading three different results
A urine EtG of 50 ng/mL falls below the 100 ng/mL threshold — this is a negative result, consistent with abstinence, with no positive band reported.
A urine EtG of 250 ng/mL falls in the 100-500 ng/mL 'very low positive' band. SAMHSA's advisory notes this range may reflect previous heavy drinking one to three days earlier, light drinking roughly 12 to 36 hours earlier, or incidental exposure to alcohol-containing products such as mouthwash or hand sanitizer — the number alone doesn't distinguish which.
A urine EtG of 1500 ng/mL is above the 1000 ng/mL line, placing it in the 'high positive' band. SAMHSA associates this range with heavy drinking on the day of testing or the day or two prior, or lighter drinking that same day — but as with every band, this is a range of plausible explanations, not a single confirmed scenario, and shouldn't be treated as an automatic finding of a violation on its own.
Questions
Can a positive EtG result come from something other than drinking alcoholic beverages?
Yes. SAMHSA's advisory specifically notes that incidental exposure to alcohol-containing products — mouthwash, hand sanitizer, certain cooking or fermented foods, some over-the-counter medications — can produce a positive EtG result, particularly in the lower bands. This is one of the central reasons a single EtG number should not be treated as unambiguous proof of drinking.
Can this result alone be used to take action against someone, like ending employment or violating probation?
SAMHSA's 2012 advisory explicitly cautions against that. It states a single EtG result should never be used alone as the sole basis for a punitive decision, precisely because the bands cover multiple plausible causes rather than one confirmed scenario. Any decision with real consequences should weigh corroborating information, program-specific protocols, and, where relevant, clinical judgment — not this number by itself.
How long after drinking can EtG be detected in urine?
Detection windows vary with how much was consumed, individual metabolism, and hydration, but EtG can generally be detected in urine for a day or more after drinking stops and, after heavier drinking, sometimes several days — considerably longer than alcohol itself remains detectable in blood or breath. That extended window is what makes EtG useful for monitoring abstinence, and also why interpreting a given number requires care rather than a simple yes/no read.
Is a 'low positive' less serious than a 'high positive'?
The bands broadly track with the likely recency and amount of exposure — higher levels are generally associated with more recent or heavier drinking, per SAMHSA's guidance — but 'low' does not mean 'ignore.' A low positive can still reflect real drinking that occurred a day or two earlier, just as it can reflect incidental exposure. The band describes a range of plausible explanations, not a severity ranking of how much a result should be trusted.
Who publishes these EtG interpretive bands, and are they official diagnostic criteria?
The bands used here come from SAMHSA's 2012 revised advisory, "The Role of Biomarkers in the Treatment of Alcohol Use Disorders." They are interpretive guidance intended to support clinical and program-level decision-making around alcohol use monitoring, not a formal diagnostic test for alcohol use disorder — diagnosis of alcohol use disorder itself relies on clinical criteria, not a biomarker level.
Does a negative EtG result (under 100 ng/mL) guarantee no alcohol was consumed?
It's the band most consistent with abstinence, but no single biomarker test offers an absolute guarantee. Timing matters — EtG clears from urine over time, so a test taken long enough after light drinking could fall below 100 ng/mL. As with the other bands, a negative result should be read as one piece of evidence, in context, rather than a categorical proof of abstinence.
References
- SAMHSA — The Role of Biomarkers in the Treatment of Alcohol Use Disorders, 2012 Revision (HHS Publication No. (SMA) 12-4686)
- SAMHSA Advisory — full text (PDF)
Read this first: This instrument computes a screening figure from population formulas — it is not a diagnosis, and it cannot see the whole picture a clinician can. Use it to inform a conversation, not to replace one.