Generality
The alcohol level (or alcohol ) represents the quantity of ethyl alcohol in the blood ; it is expressed in g / l (grams per liter) or in mg / dl (milligrams per deciliter).
There are no methods or substances that can eliminate or mask the effects of alcohol, or alter the results of the analysis (see: how to sober up).
Currently, in Italy, the legal limit of alcohol, established for driving, is 0.5 g / L (= 50 mg / dL).
What's this
Alcoholemia measures blood levels of ethanol (called ethyl alcohol or more simply alcohol in the common language).
Ethanol is contained in beverages such as beer, wine and liqueurs and, if ingested in excessive quantities, can be toxic.
When alcohol is consumed, it is absorbed from the gastrointestinal tract and transported into the body from the bloodstream. Small amounts of ethanol are eliminated in the urine or from the lungs with breathing, but most are metabolised by the liver.
The degree of alcohol intoxication may vary based on various factors, such as age, sex, weight, intake of drugs or drugs that interact with alcohol, amount of food consumed before and during drinking.
In any case, taking alcoholic beverages faster than the liver uses to metabolize them can lead to an increased concentration of ethanol in the blood. This results in the appearance of signs and symptoms such as: red eyes, impaired judgment, drowsiness and / or vomiting.
On the other hand, a very high alcohol content leads to decreased motor skills, irregular breathing, confusion and loss of consciousness.
Excessive use of alcohol for a prolonged time can lead to the development of health problems, such as liver disease and cardiovascular problems.
Factors that influence the rate of alcohol in the blood
The alcohol level of an individual depends not only on the amount of alcohol ingested, but also on many other factors, such as weight (body structure), health, age, sex and the state of fasting or satiety ( stomach contents); in fact, the human body absorbs alcohol partly through the stomach wall and partly from the intestinal tissues; the alcohol content and the stomach contents determine the speed of absorption. Furthermore, some drugs, in particular analgesics and tranquilizers, increase the negative effects of alcohol.
We all know that on an empty stomach the maximum concentration of alcohol in the blood (maximum alcohol level) is reached in a shorter time, while when the stomach is not empty the food delays the passage of alcohol to the intestine, thus, the alcohol peak is reached in longer times, which vary depending on how much you have eaten.
As you can imagine, it is impossible to do an exact preventive count, especially if the alcohol intake is not unique but, as often happens, is distributed during the meal. An indication can be obtained through this test, which allows to calculate the alcohol level in relation to height, sex and of course the amount of alcohol ingested.
For example, a concentration of 0.2 g / L of alcohol in the blood, is reached, in a subject of about 60 kilos of weight, with the ingestion on a stomach full of a 330 mL can of beer (4.5 degrees), or a 125 mL glass of wine (11.5 degrees), or a 40 mL small glass of spirits (40 degrees). Furthermore, the carbon dioxide contained in some alcoholic beverages increases the rate of alcohol absorption.
The weight of a person influences the alcohol level, since alcohol is distributed in liquid tissues; therefore, the total amount of water contained in the body influences this parameter: the greater the body weight and the greater the dilution space of the ingested alcohol; for the same weight, an individual with a lot of fat has less water than a muscular person, therefore he reaches a higher alcohol level with the same alcohol intake ingested.
It is not surprising that among the factors that influence the blood alcohol level, there is also the sex of the individual; in fact, women are more vulnerable to alcohol than men and reach higher alcohol levels with lower amounts of alcohol and with greater rapidity, since there are metabolic and physiological differences between the sexes and women have, normally, a greater quantity of adipose tissue.
For a woman, an average of 24 grams of alcohol is sufficient to reach the legal limit not to be exceeded when driving; for a man, however, this limit is reached, on average, with 36 grams of alcohol.
Why do you measure
The BAC is measured to determine if a person has consumed alcohol and to determine the amount of ethanol in the body.
The examination is generally indicated when a patient develops symptoms suggesting ethanol poisoning. Other laboratory tests, such as blood counts, glucose and electrolytes, are often required simultaneously, as there are many other conditions that can cause similar symptoms.
Normal values
Alcohol is considered normal if it is less than 0.50 g / l. However, it must be considered that an alcohol level above 0.30 g / l always causes behavioral alterations.
High alcohol level - Causes
A high blood alcohol level indicates that a person has probably taken alcoholic beverages; the concentration detected can give an indication of how serious the level of ethanol toxicity is.
Low alcohol level - Causes
A low blood alcohol level suggests that it is unlikely that the person has consumed too much alcohol. The cause of the symptoms is therefore to be found elsewhere.
The doctor will be able to indicate to which other tests to undergo to have a precise diagnosis.
How to measure it
The blood alcohol level is measured on a blood sample, obtained by taking a vein from the arm.
Note: blood is the most used sample for medical examination, but ethanol can also be determined in the breath (balloon test), urine and saliva (using a swab).
Preparation
Usually, there is no preparation for an alcohol test to ensure good sample quality.
Interpretation of Results
BAC and related symptoms
| Alcohol (g / l) * | Effects (indicative) ** |
| 0.2 | Sociability, expansiveness, redness in the face |
| 0.5 | Decreased inhibitory brakes |
| 0.8-1.2 | Depressive action on motor centers, loss of self-control and balance disorders |
| 1, 2-2, 0 | Real drunkenness, staggering gait |
| 2.0-4.0 | Loss of muscle tone, indifference to the surrounding environment, absence of reaction to stimuli, immobility, mutacism |
| > 4.0 | Unconsciousness and coma, respiratory and cardiovascular depression, death |
| (*) Alcoholemia indicates the levels of alcohol in the blood and depends primarily on the quality and quantity of the alcohol taken on (**) Indicatives, since, for the same blood alcohol level, the effects of alcohol depend on individual tolerance to the substance; in alcoholics, for example, the severity of intoxication is lower, while adolescents and women can go into an ethyl coma already exceeding 2.5 grams per liter; in children alcohol levels above 2 grams / liter can be fatal. | |
Alcoholic persons generally better control the outward manifestations of intoxication and manage to dispose of alcohol more quickly, while abstain individuals are more sensitive to lower doses of alcohol; it is probable that all this is due to a mainly psychological effect, since the sensations - which for the drinker are normal and welcome - are perceived as anomalous by the abstainer subject.
However, there is also a subjective component that determines the alterations in psychic and sensory functions relevant to driving, and this variability of reactions does not always depend on habit or addiction to alcohol: there are people who get drunk more easily of others. Some people, especially from Asian peoples, are genetically incapable of metabolizing alcohol, so they present far more serious reactions.
There are also various pathologies that interfere with the absorption and elimination of alcohol; for example those who have liver problems tend to have a higher blood alcohol content than a healthy person: this is due to alterations in the elimination of alcohol.
