To determine if a person has consumed ethanol and to measure the level of ethanol in order to detect and evaluate impairment, intoxication, or overdose
When someone has signs and symptoms that suggest intoxication or ethanol poisoning; when a person is suspected of violating drinking-related laws, or as part of a drug testing panel
A breath sample is collected by blowing into a tube or balloon. A breath sample is analyzed immediately on site using a breath-analyzer. A blood sample is obtained by inserting a needle into a vein in the arm. Urine samples are collected in sterile, plastic containers. Sometimes a single urine sample is collected and sometimes two separate samples may be collected, with the first discarded and the second collected after a measured time. Rarely, saliva samples are collected from the mouth using a swab. Blood, urine, and saliva samples must be sent to a laboratory for analysis.
Ethanol is the intoxicating ingredient in alcoholic beverages such as beer, wine, and liquor. This test measures the amount of ethanol in the blood, urine, breath, or saliva.
When ethanol is consumed, the gastrointestinal tract absorbs it. Ethanol is then carried throughout the body in the blood. The body eliminates small amounts of ethanol in the urine or from the lungs upon exhalation, but the liver processes (metabolizes) most ethanol.
The liver can process about one drink an hour, with one drink being defined as the amount of ethanol in 12 ounces of beer, 5 ounces of wine, or 1.5 ounces of whisky. A person who drinks more than one drink an hour will have an increased level of ethanol in the blood. However, certain factors affect the metabolism of alcohol, especially the amount of food consumed prior to and during drinking. The rate of metabolism can also vary with age, gender, weight, concurrent medications, and genetic status.
Drinking alcoholic beverages faster than the liver can process can result in an elevated level of ethanol in the blood. This leads to signs and symptoms of intoxication such as bloodshot eyes, flushed face, slurred speech, slow response to questions or comments, impaired judgment, decreased motor skills, drowsiness or falling asleep, and/or vomiting.
With a very high blood ethanol, more serious signs and symptoms of toxicity may appear such as confusion, stupor, staggering, irregular or slow breathing, loss of consciousness, seizures, and low body temperature (hypothermia). A very high blood ethanol can be fatal.
Long-term, excessive alcohol use can lead to the development of several medical problems such as liver disease, cardiovascular problems, depression and anxiety. (Read more about this in the article on Alcoholism.)
The ethanol test, commonly known as alcohol test, is used for both medical and legal purposes. Samples and results for each use are usually collected and tested separately.
Medical: medical testing is used to determine the level of ethanol in the blood in order to effectively treat the intoxicated person's symptoms. Blood is the most common sample used for medical alcohol tests. The tests may be ordered for a person who presents to the emergency room with signs and symptoms suggesting ethanol toxicity.
Metabolites of ethanol, including ethyl glucuronide or ethyl sufate, can also be examined. Additional tests, such as a complete blood count (CBC), glucose, and electrolyte measurement, are often ordered at the same time because there are a variety of other conditions that can cause symptoms similar to ethanol intoxication.
Overdose testing, drugs of abuse testing, and testing for the presence of other toxic alcohols such as methanol and isopropyl alcohol may also be performed if a person is suspected of ingesting or using other substances.
Legal (Forensic): legal testing is used to identify the presence of alcohol and to evaluate its presence in the context of a variety of different laws. Legal testing must have a strict chain-of-custody. Testing may be ordered to determine, for example, whether:
Post-mortem ethanol testing may be done to determine whether alcohol contributed to a person's death.
Legal ethanol testing may also be performed randomly as part of an employer's drug testing program or it may be performed "with cause" as part of an investigation after an on-the-job accident has occurred. It may also be done as part of an application for life insurance. These uses are considered legal alcohol tests because they require chain-of-custody documents.
Samples tested for legal purposes may include blood, breath, urine, and/or saliva. Breath testing is the most common test performed on drivers. It uses a conversion factor to estimate the amount of alcohol in the blood.
Blood ethanol testing may be ordered to confirm or refute findings and/or ordered as an alternative to breath testing. Urine testing may also be performed as an alternative. Usually, a person collects and discards a urine sample and then collects a second sample 20 to 30 minutes later. The amount of alcohol in the first sample will be variable because it is unknown how long the urine has been in the bladder. The second sample will reflect a timed sample and a conversion factor can then be used to estimate blood alcohol. A random urine sample is sometimes ordered to monitor people for the presence of alcohol. Saliva alcohol testing is not as widely used but may be used as an alternate screening test.
Medical ethanol testing is ordered when a person has signs and symptoms that suggest intoxication such as:
With higher blood ethanol levels, more serious signs and symptoms may appear. These may include:
Medical testing may also be done on a regular basis to ensure that a person who is being treated is not continuing to abuse ethanol.
Legal ethanol testing may be ordered when there is suspicion that a person has not followed a drinking-related law and whenever there has been an accident or unexpected death. Employment alcohol testing may be performed randomly and when the employer suspects that an employee has alcohol in his or her system while on the job. Insurance testing is primarily performed when someone is applying for a policy.
For medical testing, the detection of ethanol in a sample indicates that a person has likely been drinking, and the concentration present can give an indication of the degree of intoxication. Symptoms and complications may vary significantly from person to person. The individual's general health, age, and other medications or drugs that he or she is taking can all affect an individual's symptoms. The ability to clear the alcohol out of the body also depends on the health and function of the person's liver.
For legal testing, results obtained are compared to legal allowable limits.
The table below lists some possible interpretations of blood ethanol results:
|Blood Ethanol Result||Interpretation|
|Equal to or above 80 mg/dL (0.08%)||Legal intoxication in all states|
|80 to 400 mg/dL (0.08% to 0.40%)||Increasing impairment and depression of central nervous system likely|
|Above 400 mg/dL (>0.40%)||Loss of consciousness likely; potentially fatal|
Someone who chronically consumes significant amounts of ethanol can develop a tolerance to it and may show fewer signs and symptoms and visible impairment at a higher blood alcohol level than someone who does not consume ethanol as often.
Different ethanol sample results are not interchangeable. Breath samples are considered to be good estimates of blood alcohol concentrations in most people but can be affected by alcohol consumption within the last few minutes, ketones, released into the breath by some diabetics and dieters, and by other substances that contain alcohol, such as mouthwash and cough syrup.
Urine concentrations lag behind blood concentrations. Peak urine alcohol levels are reached 45 to 60 minutes after alcohol ingestion, at which time levels are typically about 1.3 times greater than the corresponding blood alcohol concentration, but this can be affected by various factors. Sometimes two separate samples may be collected with the first discarded and the second collected after a measured time (20-30 minutes) and tested for ethanol. This practice provides better correlation between urine and blood ethanol levels.
Urine samples that contain both glucose and bacteria or yeast (such as may be seen in some diabetics) should not be left at room temperature for extended periods of time as there is the potential for the microorganisms present to ferment the glucose in the sample and produce ethanol. This can also be seen in post-mortem samples. Occasionally, two serotonin metabolites, 5-HIAA (5-hydroxyindoleacetic acid) and 5-HTOL (5-hydroxytryptphol), may be tested to evaluate this phenomenon and confirm ethyl alcohol ingestion. An increased ratio of 5-HTOL/5-HIAA can be indicative of alcohol consumption.
Children frequently develop low blood sugar (hypoglycemia) along with ethanol poisoning, so healthcare practitioners may order blood glucose tests along with ethanol tests if they suspect ethanol toxicity in youngsters.
The Health Insurance Portability and Accountability Act (HIPAA) Privacy Rule allows healthcare providers in certain circumstances to disclose necessary medical information about a patient to law enforcement if they believe the patient presents a serious danger to himself or other people. State rules regarding release of medical test results for legal purposes vary.
A general rule of thumb is one drink equivalent an hour, but there is individual variation due to differences in factors such as race, sex, body weight, use of legal or illegal drugs that interact with alcohol, and food consumption.
No, alcohol must be metabolized and eliminated by the liver and the rate at which this happens is regulated by the liver. Food will slow the absorption of ethanol and coffee may make someone who is intoxicated feel more alert, but neither will speed up the process.
Sources Used in Current Review
2018 review completed by Lori M. Millner, PhD, NRCC, Laboratory Director, US Medical Scientific.
Jones AW. Urine as a biological specimen for forensic analysis of alcohol and variability in the urine-to-blood relationship. Toxicol Rev. 2006;25(1):15-35. PMID: 16856767.
Radu M. Nanau and Manuela G. Neuman. Biomolecules and Biomarkers Used in Diagnosis of Alcohol Drinking and in Monitoring Therapeutic Interventions. Biomolecules. 2015 Sep; 5(3): 1339–1385. Published online 2015 Jun 29. doi: 10.3390/biom5031339 PMCID: PMC4598755 PMID: 26131978.
(© 2018) ClinLabNavigator. Alcohol Urine. Available online at http://www.clinlabnavigator.com/Test-Interpretations/alcohol-urine.html?letter=A. Accessed October 2018.
Sources Used in Previous Reviews
Thomas, Clayton L., Editor (1997). Taber's Cyclopedic Medical Dictionary. F.A. Davis Company, Philadelphia, PA [18th Edition].
Pagana, Kathleen D. & Pagana, Timothy J. (2001). Mosby's Diagnostic and Laboratory Test Reference 5th Edition: Mosby, Inc., Saint Louis, MO. Pp 392-393.
Whetstone W. (2005 August 8, Updated). Breath alcohol test. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003632.htm.
(2005 December 5). Highway Safety Programs; Conforming Products List of Screening Devices to Measure Alcohol in Bodily Fluids. National Highway Traffic Safety Administration [On-line information]. PDF available for download at http://www.dot.gov/ost/dapc/testingpubs/20051205_CPL_ASD.pdf.
Harty-Golder, B. (2003 September). Liability in the lab. Medical Laboratory Observer v 35(9) [On-line journal]. Available online at http://www.mlo-online.com/articles/mlo0903liability.htm.
(2000 Updated). Alcohol Metabolism. National Institute on Alcohol Abuse and Alcoholism, Alcohol Alert no. 35; PH 371 [On-line information]. Available online at http://pubs.niaaa.nih.gov/publications/aa35.htm.
Barone, P. and Crampton, J. (2003 August). Blood Alcohol Testing: Understanding quantitative blood alcohol testing in drunk driving cases. Michigan Bar Journal [On-line journal]. Available online at http://www.michbar.org/journal/article.cfm?articleID=600&volumeID=46&viewType=live.
Kadehjian, L. (2002 June). Urine Alcohol Testing is a Valuable, Underused Tool. Clinical & Forensic Toxicology News [On-line journal]. Available online through http://www.aacc.org.
(2002 February). Urine Alcohol Testing. Marshfield Laboratories [On-line information]. Available online through http://www.marshfieldlaboratories.org.
(2004 December 20, Updated). Alcohol Intoxication Testing. North Carolina Wesleyan College, [On-line lecture]. Available online at http://faculty.ncwc.edu/toconnor/205/205lect09a.htm.
Pagana, K. D. & Pagana, T. J. (© 2007). Mosby's Diagnostic and Laboratory Test Reference 8th Edition: Mosby, Inc., Saint Louis, MO. Pp 422-423.
Brothers, E. and Doty, C. (Updated 2009 October 14). Toxicity, Ethanol. eMedicine [On-line information]. Available online at http://emedicine.medscape.com/article/1010220-overview. Accessed April 2010.
Ramachandran, T. and Gellido, C. (Updated 2009 June 15). Alcohol (Ethanol) Related Neuropathy. eMedicine [On-line information]. Available online at http://emedicine.medscape.com/article/1174146-overview. Accessed April 2010.
Grenache, D. and McMillin, G. (Reviewed 2009 May). Alcohol Abuse. ARUP Consult [On-line information]. Available online at http://www.arupconsult.com/Topics/AlcoholAbuse.html?client_ID=LTD#. Accessed April 2010.
Mayo Clinic Staff (2008 December 11). Alcohol poisoning. MayoClinic.com [On-line information]. Available online at http://www.mayoclinic.com/health/alcohol-poisoning/DS00861. Accessed April 2010.
O'Connor, P. (Revised 2008 July). Alcohol. Merck Manual for Healthcare Professionals [On-line information]. Available online at http://www.merck.com/mmpe/sec15/ch198/ch198g.html?qt=ethanol&alt=sh. Accessed April 2010.
Pagana K, Pagana T. Mosby's Manual of Diagnostic and Laboratory Tests. 3rd Edition, St. Louis: Mosby Elsevier; 2006, Pp 241-242.
50 Signs of Visible Intoxication. Oregon Liquor Control Commission. Available online at http://www.oregon.gov/olcc/docs/publications/50_signs_visible_intoxication.pdf. Last revised June 2012. Accessed June 9, 2014.
Diseases and Conditions: Alcohol Poisoning. Mayo Clinic. Available online at http://www.mayoclinic.org/diseases-conditions/alcohol-poisoning/basics/symptoms/con-20029020. Last revised July 23, 2013. Accessed June 9, 2014.
Blood Alcohol Level: Are You Legally Drunk? Nolo Network. Available online at http://dui.drivinglaws.org/drink-table.php. Accessed June 10, 2014.
Effects of Blood Alchol Concentrations. U.S. Centers for Disease Control and Prevention. Available online at http://www.cdc.gov/Motorvehiclesafety/Impaired_Driving/bac.html. Last updated February 11, 2011. Accessed June 10, 2014.
Preeti Dalawari. Ethanol Level. Medscape. Available online at http://emedicine.medscape.com/article/2090019-overview#aw2aab6b2. Last updated February 4, 2014. Accessed June 10, 2014.
Alcohol Urine. Clinical Lab Navigator. Available online at http://www.clinlabnavigator.com/alcohol-urine.html. Last updated October 6, 2013. Accessed June 10, 2014.
Message to Our Nation's Health Care Providers. U.S. Department of Health and Human Services. Available at http://www.hhs.gov/ocr/office/lettertonationhcp.pdf. Issued January 13, 2013. Accessed June 10, 2014.
Law Enforcement Access to Patients and Patient Information. University of Chicago HIPAA Program Office. Available online at http://hipaa.bsd.uchicago.edu/law_enforce.html. Issued November 26, 2007. Accessed June 10, 2014.
Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. Burtis CA, Ashwood ER, Bruns DE, eds. 4th edition. St. Louis: Elsevier Saunders; 2006, Pg 2269.