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Test ID: ALC    
Ethanol, Blood

Useful For Suggests clinical disorders or settings where the test may be helpful

Detection of ethanol (ethyl alcohol) in blood to document prior consumption or administration of ethanol

 

Quantification of the concentration of ethanol in blood correlates directly with degree of intoxication

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 80 mg/dL.

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.

Not detected (Positive results are quantified.)

Limit of detection: 10 mg/dL (0.01 g/dL)

Legal limit of intoxication is 80 mg/dL (0.08 g/dL).

Toxic concentration is dependent upon individual usage history.

Potentially lethal concentration: > or =400 mg/dL (0.4 g/dL)

Interpretation Provides information to assist in interpretation of the test results

The presence of ethanol in blood at concentrations >30 mg/dL (>0.03% or 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.

 

Blood ethanol level >80 mg/dL (>0.08%) exceeds Minnesota's legal limit for driving a motor vehicle. These levels are frequently associated with loss of manual dexterity and with sedation.

 

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.

 

Whole blood is required (not serum or plasma).

 

For chain-of-custody information, see COCH / Chain-of-Custody, Processing.

Clinical Reference Provides recommendations for further in-depth reading of a clinical nature

Porter WF, Moyer TP: Clinical toxicology. In Tietz Textbook of Clinical Chemistry. Fourth edition. Edited by CA Burtis, ER Ashwood. Philadelphia, WB Saunders Company, 1993, pp 1155-1235