Ethyl glucuronide

Ethyl glucuronide (EtG) is a direct, minor metabolite of ethanol. It is formed in the body by glucuronidation following exposure to ethanol, such as by drinking alcoholic beverages. It is used as a biomarker to test for ethanol use and to monitor alcohol abstinence in situations where drinking is prohibited, such as by the military, in professional monitoring programs (health professionals, lawyers, airline pilots), in schools, in liver transplant clinics, and in drug courts.

Formation and Elimination

Ethyl glucuronide is formed in the body by the process of glucuronidation, which is a major part of phase II of drug metabolism. This process involves the transfer of glucuronic acid, a sugar molecule, to the ethanol molecule. This reaction is catalyzed by the enzyme UDP-glucuronosyltransferase (UGT).

Once formed, ethyl glucuronide is eliminated from the body primarily through urine. It can also be detected in blood, hair, and nails.

Detection

Ethyl glucuronide can be detected in the urine up to 80 hours after ingestion of ethanol. This makes it a valuable tool for monitoring alcohol abstinence, as it provides a much longer detection window compared to direct measurement of ethanol.

The detection of ethyl glucuronide in urine is performed using immunoassay screening methods, followed by confirmation with gas chromatography-mass spectrometry (GC-MS) or liquid chromatography-tandem mass spectrometry (LC-MS/MS).

Limitations

While ethyl glucuronide is a specific marker for ethanol ingestion, it is not a perfect test. False positives can occur due to the presence of certain types of bacteria in the urine that can produce ethanol and thus ethyl glucuronide. In addition, exposure to ethanol from non-beverage sources, such as mouthwash or hand sanitizer, can also result in positive ethyl glucuronide tests.

See Also

• Ethanol metabolism
• Alcohol (drug)
• Biomarker (medicine)