What are the implications and recommended actions for an individual with high ethyl glucuronide (EtG) and high ethyl sulfate (EtS) on a urine drug screen (UDS)?

High Ethyl Glucuronide and Ethyl Sulfate on UDS Indicates Recent Alcohol Consumption

High ethyl glucuronide (EtG) and ethyl sulfate (EtS) on a urine drug screen strongly indicate alcohol consumption within the past 3 days, requiring immediate assessment for alcohol use disorder and appropriate intervention. 1

Understanding EtG and EtS as Alcohol Biomarkers

Ethyl glucuronide (EtG) and ethyl sulfate (EtS) are direct metabolites of alcohol that remain detectable in urine for significantly longer periods than ethanol itself:

• Detection window: Up to 80 hours (approximately 3 days) after alcohol consumption 1
• Sensitivity: 76-89% for EtG and 82% for EtS 1
• Specificity: 93-99% for EtG and 86% for EtS 1

These biomarkers are superior to traditional markers like GGT, AST, ALT, MCV, and CDT for detecting recent alcohol use. They are particularly valuable because they can detect alcohol consumption even after ethanol is no longer present in blood or breath tests 2.

Clinical Implications

1. Confirmed recent alcohol use: High levels of both EtG and EtS provide strong evidence of alcohol consumption within the past 3 days 1

2. Hidden alcohol consumption: In patients who deny drinking, positive EtG/EtS can reveal concealed alcohol use. Studies show that 54.5% of patients with positive EtG had negative breath alcohol tests and denied alcohol consumption 2

3. Relapse detection: EtG/EtS testing significantly improves detection of relapses in alcohol-dependent patients, with studies showing 12-28% of patients denying relapse actually testing positive 3

4. Predictive of treatment outcomes: Patients testing positive for EtG/EtS have significantly higher dropout rates from treatment programs 3

Recommended Actions

1. Immediate clinical assessment:

   • Evaluate for signs and symptoms of alcohol withdrawal
   • Assess for alcohol use disorder using validated tools (AUDIT, AUDIT-C)
   • Screen for liver disease and other alcohol-related complications

2. Patient discussion:

   • Present the test results in a non-confrontational manner
   • Discuss the significance of positive EtG/EtS as objective evidence of recent alcohol consumption
   • Avoid using biomarkers to "catch" or punish patients, but rather as catalysts for therapeutic discussion 1

3. Treatment planning:

   • For patients with alcohol use disorder: Offer brief intervention, pharmacotherapy, and referral to specialized treatment 1
   • For liver transplant candidates/recipients: Involve multidisciplinary team including transplant hepatologist, psychologist, psychiatrist, and addiction specialist 1
   • Consider ongoing monitoring with EtG/EtS testing to support recovery and abstinence

4. Follow-up monitoring:

   • Implement regular EtG/EtS testing as part of ongoing monitoring
   • Consider complementary testing with phosphatidylethanol (PEth) in blood, which has a longer detection window (2-3 weeks) 1

Important Caveats and Potential Pitfalls

1. False positives:

   • Very low levels of EtG (<0.1 mg/L) may result from incidental alcohol exposure (mouthwash, hand sanitizers, certain foods) 1
   • Using a higher cutoff (typically >500 ng/mL for EtG and >75 ng/mL for EtS) reduces false positives while maintaining high sensitivity 1

2. Renal function considerations:

   • Urinary EtG and EtS detection times can be prolonged in patients with renal failure 1
   • Consider this when interpreting results in patients with kidney disease

3. Test limitations:

   • Cannot determine the exact amount of alcohol consumed
   • Does not differentiate between a single heavy drinking episode and multiple moderate drinking episodes
   • Provides information only about recent consumption, not long-term patterns

4. Complementary testing:

   • For longer-term monitoring (up to 6 months), consider hair EtG testing 1
   • For monitoring over 2-3 weeks, blood phosphatidylethanol (PEth) testing is valuable 1

By following these recommendations, clinicians can effectively use EtG and EtS results to guide appropriate interventions for patients with alcohol use issues, potentially improving outcomes related to morbidity, mortality, and quality of life.