Alcohol can be detected in breath as well as in all body fluids. The type of testing used to detect alcohol will depend upon the intended use of the results and the testing agency. If testing under a criminal justice system, non-regulated workplace testing, or recovery programs, urine is an acceptable specimen. The most common compounds to test for the presence of alcohol in urine are ethanol (alcohol) and Ethyl glucuronide (EtG). Ethanol is used more frequently, but the use of EtG is growing.
Ethanol has a relatively short window of detection in urine. The normal clearance of ethanol from the urine is 8-12 hours. Fermentation produces ethanol. Any urine specimen with a glucose positive in conjunction with an ethanol positive should be ruled as an invalid specimen due to the presence of glucose. Individuals who are diabetic can often have glucose in their urine.
Ethyl glucuronide or EtG is a metabolite only produced when alcohol is in the bloodstream, and is referred to as a biomarker. The more alcohol a person consumes, the greater amount of EtG markers are present in the hair or urine sample. EtG can be detected in urine up to 4-5 days after drinking alcohol, and can be detected in all body fluid as well as hair.
EtG can provide a longer detection period, and is not affected by fermentation in diabetics. However, with some initial lower cut-off levels there were concerns of incidental exposure. A higher cut-off level for EtG testing addressed this issue.
Urine samples are screened using an enzyme immunoassay method and if the results are greater than 500 ng/mL, they are then confirmed using gas chromatography/mass spectrometry (GS/MS). The 500 ng/mL is also the cut-off level for GC/MS confirmation.