At a Glance
Why Get Tested?
To determine if a person has consumed ethanol and to measure the amount of ethanol present
When to Get Tested?
When someone has symptoms that suggest ethanol toxicity or when a person is suspected of violating drinking-related laws or as part of a drug testing panel
Ethanol may be determined from a blood sample, a urine sample, a saliva sample or a breath sample. Blood, urine, and saliva samples must be sent to a laboratory for analysis. A breath sample is analyzed immediately on site using a Breathalyzer.
Test Preparation Needed?
The Test Sample
What is being tested?
This test measures the amount of ethanol in the blood, urine, breath, or saliva. Ethanol (also called ethyl alcohol or alcohol) has been consumed by civilizations throughout the world for thousands of years. Small amounts of ethyl alcohol can cause euphoria, relaxation, and decreased inhibition. Moderate amounts can cause impaired judgment and decreased motor skills; large amounts in a relatively short period of time can cause acute ethanol toxicity with disorientation, depressed breathing, coma, and even death. Chronic ingestion of large quantities of alcohol can lead to alcoholism and to permanent liver damage.
When ethanol is consumed, it is absorbed by the gastrointestinal tract and carried throughout the body in the bloodstream. Small amounts of ethanol are excreted in the urine or exhaled from the lungs, but most is metabolized by the liver. The liver considers ethanol a toxin. With the help of enzymes, it oxidizes the alcohol first to acetaldehyde, then to acetate, and then finally to carbon dioxide and water. 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 increased levels of ethanol in their blood stream.
How is the sample collected for testing?
A blood sample is obtained by inserting a needle into a vein in the arm; a breath sample is collected by blowing into a tube or balloon. Urine samples are collected in 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. Saliva samples are often collected from the mouth using a swab.
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed.
Ask a Laboratory Scientist
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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.
Sources Used in Current Review
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 through http://emedicine.medscape.com. 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 through http://emedicine.medscape.com. 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# through http://www.arupconsult.com. 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 through http://www.mayoclinic.com. 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 through http://www.merck.com. 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.
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 through http://www.dot.gov.
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 through http://www.mlo-online.com.
(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 through http://pubs.niaaa.nih.gov.
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 through http://www.michbar.org.
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 through http://faculty.ncwc.edu.