Urine EtG testing isn’t only about a single number. Cutoff, dilution, and creatinine correction all influence how results are interpreted.

What is a cutoff?

A cutoff is the threshold above which a result is considered positive. Programs may use 100, 200–300, or 500 ng/mL. Lower cutoffs catch more low‑level signals but can increase positives from distant drinking.

Dilution & specific gravity

When urine is very dilute (e.g., after heavy water intake), the concentration of EtG per milliliter drops. Labs often check specific gravity or creatinine to judge whether a sample is dilute.

Creatinine correction

Some reports normalize EtG to creatinine (e.g., EtG/Cr). This helps account for urine concentration and can make longitudinal comparisons more meaningful.

Example illustration

Two samples with the same EtG amount:

  • Sample A: Dilute urine → lower EtG (ng/mL), may look “lower” than expected.
  • Sample B: Concentrated urine → higher EtG (ng/mL).
    Creatinine‑normalized values reduce this discrepancy.

EtG + EtS for confidence

Testing EtG alongside EtS supports interpretation and can reduce misclassification due to instability or contamination issues.

Incidental exposures

Policies vary, but most programs look at the overall pattern, timing, and companion markers (e.g., EtS, creatinine) rather than any single reading in isolation.

Practical takeaways

  • Know your program’s cutoff and reporting format (with or without creatinine correction).
  • Hydration affects measured concentration; extreme dilution may prompt additional scrutiny.
  • Interpreting results in context (EtG + EtS + creatinine + timing) is more reliable.

FAQ

Q: What does creatinine correction actually do? A: Creatinine correction (EtG/Cr ratio) helps account for urine concentration. It makes results more comparable between samples and can reveal true EtG levels even in diluted urine.

Q: Can I dilute my urine to lower EtG levels? A: While dilution can lower EtG concentration, labs check for this using creatinine or specific gravity. Overly diluted samples may be flagged as invalid or suspicious.

Q: What’s considered a “normal” creatinine level? A: Normal urine creatinine is typically 20-300 mg/dL. Values below 20 mg/dL suggest significant dilution, while very high values might indicate concentration.

Q: Why do some labs test EtG and EtS together? A: EtS provides confirmation and reduces false positives. It’s more stable than EtG and helps labs distinguish between true positives and potential contamination or degradation.

Q: What cutoff level does my program use? A: Common cutoffs are 100, 200-300, or 500 ng/mL. You should ask your program coordinator, as this significantly affects detection windows.

Q: Can medications or foods cause positive EtG tests? A: Most medications and foods contain minimal alcohol that won’t cause positives at standard cutoffs. However, liquid medications with high alcohol content or excessive use might contribute to EtG levels.

Q: What happens if my sample is too diluted? A: Programs handle this differently. Some may consider it a positive result, others require retesting, and some have specific dilution policies. Check your program’s guidelines.

Q: How long do labs store EtG samples? A: Storage varies, but EtG can degrade over time, especially if not properly refrigerated. Fresh samples provide the most accurate results.

Disclaimer

This article is for educational purposes only and does not provide medical, legal, or employment advice.