Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Ethanol is the single most important substance of abuse in the United States. It is the active agent in beer, wine, vodka, whiskey, rum, and other liquors.
Ethanol acts on cerebral functions as a depressant similar to general anesthetics. This depression causes most of the typical symptoms such as impaired thought, clouded judgment, and changed behavior. As the level of alcohol increases, the degree of impairment becomes progressively increased.
In most jurisdictions in the United States, the level of prima facie evidence of being under the influence of alcohol for purposes of driving a motor vehicle is a blood ethanol concentration 80 mg/dL (0.08 g/dL; 0.08%; 800 mcg/dL).
In the context of medical/clinical assessment, serum is submitted for analysis. On average, the serum concentration of the alcohols is 1.2-fold higher than blood. The serum would contain approximately 0.10 g/dL of ethanol in a blood specimen that contains 0.08 g/dL ethanol.
Detection of ethanol (ethyl alcohol) in serum to document prior consumption or administration of ethanol. Quantification of the concentration of ethanol in serum correlates with degree of intoxication.
Legal limit of intoxication in Massachusetts is 80 mg/dL (0.080%). The presence of ethanol in blood at concentrations >30 mg/dL (>0.03% or 0.03 g/dL) is generally accepted as a strong indicator of the use of an alcohol-containing beverage.
Blood ethanol levels >50 mg/dL (>0.05%) are frequently associated with a state of increased euphoria.
A blood alcohol level > or =400 mg/dL (> or =0.4) may be lethal as normal respiration may be depressed below the level necessary to maintain life.
The blood ethanol level is also useful in diagnosis of alcoholism. A patient who chronically consumes ethanol will develop a tolerance to the drug and requires higher levels than described above to achieve various states of intoxication. An individual who can function in a relatively normal manner with a blood ethanol level >150 mg/dL (>0.15%) is highly likely to have developed a tolerance to the drug achieved by high levels of chronic intake.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
Not intended for use in employment-related testing or issues regarding legal ethanol intoxication.
On average, the serum concentration of the alcohols is 1.2-fold higher than blood. For example, the serum would contain approximately 0.10 g/dL of ethanol in a blood sample that contains 0.08 g/dL ethanol.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
None detected (Positive results are quantitated.)
Toxic concentration: > or =400 mg/dL
Clinical References Provides recommendations for further in-depth reading of a clinical nature
1. Caplan YH: In Forensic Science Handbook. Vol 1. Edited by R Saferstein. Englewood Cliffs, Prentice Hall, 1982
2. Goodman and Gilman's: The Pharmacological Basis of Therapeutics. 7th edition. Edited by TW Rall, F Murad. New York, McMillan Publishing, 1985
3. Porter WF, Moyer TP: Clinical toxicology. In Tietz Textbook of Clinical Chemistry. 4th edition. Edited by CA Burtis, ER Ashwood. Philadelphia, WB Saunders Company, 1993, pp 1155-1235
4. Principles of Forensic Toxicology. Edited by B Levine. Washington DC, American Association of Clinical Chemistry, 1999