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 a patient 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 analysed immediately on site using a Breathalyser
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 civilisations throughout the world for thousands of years. Small amounts of 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 metabolised 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 standard drink an hour, although this varies from person to person – with one standard drink being defined as the amount of drink containing 10g of alcohol (ethanol). A person who drinks more than 1 drink an hour will have a build up of ethanol in their blood stream.
Number of standard drinks - beer
Number of standard drinks for other beverages
eg. sherry or port
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.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed.
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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.