EtG Cutoff Levels: Interpret ROC Evidence for Clinicians and Employers

by Stephanie October 07, 2026

EtG test results hinge on which cutoff a lab uses: 100 and 200 ng/mL thresholds catch light drinking and extend detection windows but flag more incidental exposures, while 500 and 1000 ng/mL thresholds favor specificity and point toward heavier, more recent drinking. A result above a high threshold usually signals substantial recent alcohol intake, while anything between 100 and 500 ng/mL needs context, timing, and often a confirmatory EtS test before anyone draws conclusions.

TL;DR:

Using a 100 or 200 ng/mL cutoff detects more recent or light drinking but increases false positives from incidental exposure.

Results above 1000 ng/mL typically indicate heavy drinking within the past day or two, regardless of cutoff.

Lower cutoffs extend detection windows up to five days, but also raise false alarms, making confirmatory testing crucial for borderline cases.

Individual factors like hydration, metabolism, and recent product use significantly influence EtG levels, requiring context before interpretation.

Lab confirmation using LC-MS/MS or EtS testing is recommended for high-stakes decisions, especially for low positive results.

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Common EtG cutoff levels and what they tell you
How cutoff choice shapes detection windows and accuracy
What changes EtG concentrations, and how to read them
Confirmatory testing: EtS, LC-MS/MS, and reading the report
Reading real results: short cases and suggested phrasing
Where test kits and lab confirmation fit into this picture
Fair interpretation matters as much as the number itself
Get the right EtG test or lab confirmation for your situation
FAQ
Sources

Common EtG cutoff levels and what they tell you

Labs don’t report a single pass or fail line. They work with interpretive bands that reflect how much ethyl glucuronide shows up in urine and what that concentration tends to mean.

Clinical research on alcohol-dependent outpatients classifies results into three practical bands: high (above 1000 ng/mL), low (500 to 1000 ng/mL), and very low (100 to 500 ng/mL), each tied to a different likelihood of recent or heavy drinking according to research on light and heavy drinking detection.

High (>1000 ng/mL): frequently reflects heavy drinking within the past one to two days.
Low (500 to 1000 ng/mL): can point to recent light drinking or residual signal from a heavier session a day or two earlier.
Very low (100 to 500 ng/mL): may reflect light drinking, the tail end of heavier use, or incidental exposure to ethanol-containing products.

Many laboratories default to a 500 ng/mL screening cutoff, which is also the threshold Mayo Clinic Laboratories uses for its standard EtG screen. That default shapes what gets reported as positive in the first place, so a drinking episode that would register at a lower cutoff can clear the system before a 500 ng/mL screen ever catches it.

How cutoff choice shapes detection windows and accuracy

Choosing a cutoff is really choosing a trade-off between catching more drinking episodes and avoiding false alarms from trace exposure. Lower cutoffs extend how long a test stays positive after drinking, but they also pick up more noise.

One analysis found a 100 ng/mL cutoff detected a high majority of light drinking episodes at two days post-use, while a 500 ng/mL cutoff detected far less beyond 24 hours, with light-drinking detection dropping to a moderate level between two and five days, according to research on urinary EtG detection. That gap matters enormously for anyone trying to interpret a single result without knowing which cutoff produced it.

Separate ROC curve analysis across 24 to 120 hours backs up this pattern. Sensitivity at a low cutoff ranged from high to moderate as time passed, while specificity ranged from lower to moderate, meaning the lowest cutoff catches the most true positives but also produces more false alarms. A 200 ng/mL cutoff improved specificity while keeping sensitivity reasonable, which is why researchers recommend it as a workable middle ground for many clinical and research applications, per findings on EtG cutoff determination.

For settings where missing a drinking episode carries real consequences, such as monitoring in addiction treatment, a lower cutoff makes sense. For workplace or forensic testing, where a false positive can cost someone a job, a higher cutoff like 500 ng/mL reduces that risk at the expense of catching lighter or older drinking. If you want a deeper breakdown of how these windows play out hour by hour, our EtG detection time guide walks through the timing in more detail.

What changes EtG concentrations, and how to read them

A single EtG number never tells the whole story. Dose, frequency, and individual physiology all shift how much ethyl glucuronide shows up and for how long.

Heavier or repeated drinking extends the detection window, and chronic drinkers can test positive well beyond the short window a single light drink would produce.
Incidental exposure from hand sanitizer, mouthwash, or fermented foods can push a result into the very low or low range without any intentional drinking, which is why context matters before anyone treats a borderline result as proof of use.
Urine dilution lowers measured concentration regardless of actual intake, so labs often check creatinine levels to confirm a sample isn’t too dilute to interpret reliably.

Metabolism, hydration, and kidney function all affect how quickly ethyl glucuronide clears the body, which means two people who drank the same amount can produce different EtG readings. If someone reports recent mouthwash or sanitizer use, our piece on whether mouthwash can cause a failed alcohol test covers how much exposure it typically takes to register.

Pro Tip: Never treat a single low-positive EtG result as definitive proof of drinking: ask about recent product exposure and consider a repeat or confirmatory test first.

Confirmatory testing: EtS, LC-MS/MS, and reading the report

Screening immunoassays are fast and inexpensive, but they’re not the final word, especially on borderline results. Confirmatory testing exists precisely to settle the cases a screen can’t resolve on its own.

Immunoassays run at variable cutoffs and are designed for rapid screening, not legal or clinical certainty on their own.
LC-MS/MS confirmation offers a lower limit of quantitation and far greater specificity, which is why Mayo Clinic Laboratories lists a confirmatory cutoff around 250 ng/mL even though its screening cutoff sits at 500 ng/mL, per its EtG test catalog.
Measuring ethyl sulfate (EtS) alongside EtG helps separate incidental exposure from actual ingestion, since EtS is less likely to appear from certain environmental sources, according to clinical trial data on EtG and EtS assays.

Confirmation matters most when a result sits in the very low or low band and the consequences of being wrong are significant, whether that’s a clinical treatment decision or an employment outcome. A quantitative confirmatory report, paired with an explicit cutoff and clear interpretation, helps prevent misreading by nontechnical readers.

Reading real results: short cases and suggested phrasing

Numbers only mean something in context. Here’s how a few common scenarios typically play out.

A single drink 12 to 24 hours before testing, result of 300 ng/mL: this falls in the very low band and is consistent with light, recent drinking. Suggested phrasing: “Result consistent with light alcohol consumption within the prior 24 hours; no confirmatory testing indicated absent policy requirement.”
A result of 1200 ng/mL: this falls solidly in the high band and is consistent with heavier recent drinking. Suggested phrasing: “Result consistent with recent heavy alcohol consumption; recommend quantitative confirmatory testing and clinical follow-up.”
A result of 150 ng/mL following reported hand sanitizer use: this very low result warrants scrutiny before any conclusion. Suggested phrasing: “Very low positive result; incidental exposure cannot be excluded. Recommend EtS confirmation and repeat testing if clinically indicated.”

Pro Tip: Document the reported timeline, the cutoff used, and whether confirmatory testing was ordered. That record is what protects both the tested individual and the person interpreting the result.

Readers managing a liver condition alongside alcohol monitoring may also find it useful to track broader markers of liver function over time, as outlined in this practical guide to monitoring liver health.

Where test kits and lab confirmation fit into this picture

We stock EtG screening devices built around the cutoffs covered here, including rapid dipcards set at a 300 ng/mL threshold, which land squarely in the very low to low interpretive range discussed above. A 300 ng/mL dipcard is useful for quick screening, but it carries the same limitation as any immunoassay: it flags a result without confirming the cause.

For anyone who needs a definitive answer, lab confirmation through certified facilities adds the quantitative precision a dipcard can’t provide. Our EtG test collection includes both rapid screening options and the lab pathway for cases that need LC-MS/MS or EtS confirmation.

Fair interpretation matters as much as the number itself

A low EtG result is not proof of intent to drink, and treating it that way invites unfair outcomes. We believe anyone being tested deserves to know the cutoff being applied before the sample is collected, not after a borderline result shows up.

Confirmatory testing for low positives isn’t bureaucratic overhead. It’s what separates a defensible decision from a guess dressed up as a number.

— Alan

Get the right EtG test or lab confirmation for your situation

Choosing between a rapid dipcard and full lab confirmation comes down to how much certainty you need. A quick screen works for routine checks, but anything with real consequences, a treatment decision, an employment matter, or a legal question, calls for quantitative lab results from a certified facility.

At-home EtG dipcards give a fast, low-cost first read for routine or personal monitoring.
Our lab testing services provide LC-MS/MS confirmation and EtS analysis through SAMHSA, ISO, CLIA, and CAP compliant labs.
We offer shipping and a satisfaction guarantee on orders.

Whether you’re screening at home or need a defensible, lab-confirmed result, our lab testing services page is the place to start.

This article is general information, not a substitute for advice from a qualified doctor. Consult a qualified healthcare professional about your own circumstances before acting on anything here.

FAQ

What does the presence of ethyl sulfate in urine indicate?

Ethyl sulfate (EtS) is a specific metabolite of ethanol, so its presence alongside EtG helps confirm actual alcohol ingestion rather than incidental exposure, according to research on EtG and EtS assays. Labs sometimes add EtS testing to a low-positive EtG result to increase confidence in the interpretation.

Is 150 a high alcohol level?

No, a result of 150 ng/mL falls into the very low interpretive band, which can reflect light drinking, the tail end of a heavier session, or incidental exposure rather than heavy use, based on interpretive bands from clinical research. Context and, when needed, EtS confirmation help clarify what a result in this range actually means.

Is 80 hours enough to pass an EtG test?

There’s no fixed “80-hour rule” that applies reliably across individuals, since detection windows vary by dose, drinking pattern, and how an individual metabolizes alcohol, per clinical trial data on EtG assays. Light drinking can clear within 24 hours, while chronic heavy drinking may remain detectable for several days.

What are some common myths about EtG detection?

One common myth is that a fixed number of hours guarantees a clean result, when detection actually depends on dose, cutoff used, and individual physiology. Another is that any positive result proves intentional drinking, when incidental exposure from products like hand sanitizer or mouthwash can also produce a low positive, as explained in our guide on mouthwash and alcohol test results.