What is Alcohol Blood test?
Alcohol blood test measures the levels of alcohol circulating in your bloodstream.
Although a breath analyser is a faster method for analysing alcohol levels in body, a blood test is more accurate.
All the alcohol absorbed in the blood is processed by the liver. However, liver can process only one drink in an hour; therefore, if you drink faster than this rate, you will start to feel the effects of alcohol intoxication. The level of alcohol in your blood remains high for 30-90 minutes after your last drink.
An alcohol blood test can be done to check for alcoholism or to ascertain the levels of alcohol intoxication in drunk drivers. In children, it can help diagnose alcohol poisoning. Generally, alcohol poisoning is accidental. Young children may consume alcohol from the following:
Most cases of alcohol poisoning seen in children are due to intake of mouthwash or cologne.
- Why is Alcohol blood test performed?
- How do you prepare for Alcohol Blood test?
- How is an Alcohol Blood test performed?
- Alcohol Blood test results and normal level/range
Why is Alcohol blood test performed?
The alcohol screening test may be ordered if an individual is suspected of driving while intoxicated. The symptoms of alcohol intoxication are as follows:
- Slowed reflexes
- Difficulties in balance and coordination
- Nausea and vomiting
- Slurred speech
- Poor judgement
- Mood changes
This test may also be required when children show symptoms of alcohol poisoning. Apart from the previously mentioned signs of intoxication, other symptoms of alcohol poisoning are as follows:
- Irregular breathing
- Low body temperature
- Confusion
- Seizures
The blood test can also help to determine if:
- You have been drinking and driving
- You have consumed alcohol while on a treatment regimen that prohibits drinking
- You have alcohol poisoning
Alcohol blood test may also be ordered in your workplace during a random drug test.
In case of an accident, this test may be ordered to check if you had consumed alcohol.
How do you prepare for Alcohol Blood test?
You do not need to have any special preparation for this test. Inform your doctor about any medicines, vitamins, supplements and herbs that you are taking. Also, tell him/her if you are taking any over-the-counter or illegal drugs.
Timing is really crucial for this test. Accurate results show up when the testing is done within a six- to 12-hours of the last drink. If you get the test too early or too late, your results will be inaccurate.
How is an Alcohol Blood test performed?
For this test, your doctor will withdraw a sample of your blood from a vein in your arm.
Though blood tests are completely safe, some people experience mild bruising or pain at the needle insertion site for a while after the test. In most cases, these symptoms subside on their own. If the discomfort doesn’t go away or if you notice an infection developing at the site, please check in with your doctor.
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Alcohol Blood test results and normal level/range
Normal results:
If your blood alcohol content is 0.0 g/dL, you are considered sober.
Abnormal results:
Some of the values for blood alcohol percentage with their effects are as follows:
| Blood alcohol percentage (%) | Effects |
| 0.01-0.07 |
|
| 0.08-0.13 |
|
| 0.14-0.19 |
|
| 0.20-0.24 |
|
| 0.25-0.29 |
|
| 0.30-0.34 |
|
| 0.35 and higher |
|
In India, the legally acceptable amount of blood alcohol content that is permissible for drivers is up to 0.03%.
Your blood alcohol content is dependent on the following factors:
- The amount of alcohol you consumed
- Rate of consumption
- Hydration levels
- Your weight
- Your gender
- Type of drink
- Food in your stomach
- Presence of other drugs in your system
Disclaimer: All results must be clinically correlated with the patient’s complaints to make a complete and accurate diagnosis. The above information is provided from a purely educational point of view and is in no way a substitute for medical advice by a qualified doctor.
References
- Hinkle J, Cheever K. Brunner & Suddarth’s Handbook of Laboratory and Diagnostic Tests. 2nd Ed. Philadelphia: Wolters Kluwer Health, Lippincott Williams & Wilkins; 2014: 278 p.
- Centers for Disease Control and Prevention [internet]. Atlanta (GA): US Department of Health and Human Services; Frequently Asked Questions
- National Institute on Alcohol Abuse [internet]. National Institute of Health. Bethesda. Maryland. US; Alcohol's Effects on Health
- National Heart, Lung, and Blood Institute [Internet]. Bethesda (MD): U.S. Department of Health and Human Services; Blood Tests
- UW Health: American Family Children's Hospital [Internet]. Madison (WI): University of Wisconsin Hospitals and Clinics Authority; Blood Alcohol
- University of Rochester Medical Center [Internet]. Rochester (NY): University of Rochester Medical Center; Ethanol (Blood)
- Bowling Green State University [Internet]. Ohio. US; Factors that Affect Intoxication
- Office of Alcohol Policy and Education [Internet]. Stanford University. Stanford. California. US; Factors that affect how alcohol is absorbed & metabolized
- National Health Service [internet]. UK; Blood Tests
- College of Saint Benedict [internet]. St. Joseph. Minnesota. Saint John's University; Understanding Blood Alcohol Content (BAC)
- World Health Organization [Internet]. Geneva (SUI): World Health Organization; Legal BAC limits by country




