How long should you not drink alcohol before a blood test

Blood tests are one of the most reliable methods for detecting heavy alcohol consumption. They can also effectively measure blood alcohol content (BAC).

While effective, there are a few things to know about the tests before accepting the results.

In the U.S., one-fifth of patients in primary care clinics report drinking alcohol to the point where it can harm their health. However, one-fourth of people also report binge drinking within the past month.

Research also shows that people who drink unhealthy amounts of alcohol tend to underestimate how much they consume. This makes blood testing a useful tool for measuring realistic alcohol consumption, especially for those seeking treatment. 

Testing is also used in health care for people managing conditions related to alcohol consumption, such as liver disease or damage.

Direct and Indirect Biomarkers 

Most blood tests rely on direct and indirect biomarkers, which show how a person’s organs function. 

Indirect biomarkers are affected by alcohol consumption, but alcohol is not the only thing that can affect them. 

Direct biomarkers, on the other hand, only arise after alcohol consumption. This makes them an accurate predictor of the amount of alcohol someone has recently consumed. 

In the past, blood tests relied on indirect markers to determine BAC. In some cases, indirect biomarker tests are as low as 44 percent accurate.

Direct biomarker testing is approximately 99 percent accurate. The results from a direct biomarker blood test are even more reliable when confirmed through fingernail and hair testing results. 

Summary

Blood tests are useful tools used in measuring blood alcohol concentration. Between direct and indirect biomarkers, direct biomarkers are considered more accurate, with an accuracy rate of 99 percent.

CDT Testing for Alcohol Abuse

CDT Testing, which is short for carbohydrate-deficient transferrin, is an alcohol biomarker test.

Transferrin is a substance in the blood that carries iron to the bone marrow, liver, and spleen. When someone drinks too much, it increases certain types of transferrin that are carbohydrate-deficient.

It also helps determine if someone is: 

CDT testing works by measuring the amount of carbohydrate-deficient transferrin in a person’s system. Moderate drinkers or non-drinkers have lower levels of carbohydrate-deficient transferrin. 

Heavy drinkers drink four or more drinks per day (at least five days a week for two weeks before the test). These people tend to have significantly higher levels of carbohydrate-deficient transferrin.

Effectiveness of CDT Tests

CDT testing is accurate, but not foolproof.

This is because heavy drinking doesn’t trigger an increase in carbohydrate-deficient transferrin for everyone. If someone suspected of drinking has low carbohydrate-deficient transferrin, medical professionals encourage follow-up use of other alcohol biomarker tests for the most accurate results.

Despite it being imperfect, CDT testing is the only test sensitive enough to detect relapse or reduction in alcohol use. Many therapists use CDT testing to determine a baseline level for patients when treatment begins.

Summary

Carbohydrate-deficient transferrin (CDT) is an alcohol biomarker test. Although not completely perfect, it is a very sensitive test that is able to detect a relapse or a decrease in alcohol consumption.

Alcohol Use Biomarkers

Other biomarker tests support or disprove the results of a CDT test. Selecting the proper test varies from person to person. 

The best tests are easy to obtain, inexpensive to evaluate, and acceptable to patients and therapists. 

Biomarkers differ based on several factors, including:

• Age
• Gender
• Ethnicity
• Health status

The specific markers used to detect a high level of alcohol exposure include:

• Ethanol
• Ethyl sulfate (EtS)
• Ethyl glucuronide (EtG)

Specific markers for chronic alcohol use include:

• Carbohydrate-deficient transferrin (CDT)
• Phosphatidylethanol (PEth)

Nonspecific markers include: 

• Aspartate aminotransferase (AST)
• Alanine aminotransferase (ALT)
• Gamma-glutamyl transferase (GGT)
• Mean corpuscular volume (MCV)

Each biomarker testing method has advantages and disadvantages. Experts recommend using a combination of tests to confirm the status of a person’s alcohol intake.

Summary

There are many types of biomarkers used to measure blood alcohol concentration. Factors like age, gender, health status, and ethnicity affect different biomarkers. Use a combination of different biomarker tests to get accurate results.

If you are getting blood work done, it's best to avoid alcohol consumption, especially for fasting blood tests. Drinking alcohol can cause irregular enzyme, blood sugar, and fat levels and give inaccurate blood test results.

Avoid drinking alcohol before taking these common blood tests:

• Cholesterol tests
• Triglyceride tests
• Lipid panel blood tests
• Blood glucose tests
• Hepatitis tests
• Liver function tests

If you have a blood test coming up and are unsure whether you can drink or not, it's best to avoid drinking any alcohol at all, especially the night before.

Consult a health care professional for more medical advice if you have further questions or want to explore treatment options/resources.

Alcohol Use Statistics

Related Pages

Updated on March 11, 2022

How long alcohol stays in your system depends on a number of factors. A big concern that many people have after a long night of drinking is how long alcohol will remain in their system. It takes time for alcohol to be processed by the body. On average, it takes about one hour to metabolize one standard drink. In terms of determining exactly how long alcohol is detectable in the body depends on many factors, including which kind of drug test is being used.

• Blood: Alcohol is eliminated from the bloodstream at about 0.015 per hour. Alcohol can show up in a blood test for up to 12 hours.
• Urine: Alcohol can be detected in urine for up 3 to 5 days via the ethyl glucuronide (EtG) test or 10 to 12 hours via the traditional method.
• Hair: Similar to other drugs, alcohol can be detected in a hair follicle drug test for up to 90 days.

Reach out to a treatment provider for free today for immediate assistance.

How The Body Processes Alcohol

The body follows a pretty straightforward process when digesting and metabolizing alcohol. Therefore, the amount of time that a drink will stay in someone’s system has more to do with how much a person drinks than any other factor.

Once swallowed, alcohol enters the digestive system and travels to the stomach and small intestine. Approximately 20% of alcohol is absorbed through the stomach, and most of the remaining 80% is absorbed in the small intestine, then directly to the bloodstream. Once in the blood, alcohol is rapidly transported throughout the entire body, which is why alcohol impacts so many different bodily systems. Most of the alcohol that enters the body eventually ends up in the liver, where the vast majority of alcohol metabolism takes place. In general, the liver can process one ounce of liquor (or one standard drink) in one hour. If an individual consumes more than this, the system becomes saturated, and the additional alcohol will accumulate in the blood and other tissues until it can be metabolized. If this happens too many times or too fast, damage to the brain and tissues of the body can develop.

The human body is very effective at processing alcohol, provided that alcohol is not consumed so quickly as to cause alcohol poisoning. It is estimated that between 90% and 98% of all alcohol that enters the body is metabolized and absorbed. The remaining alcohol is then expelled from the body through sweat, urine, vomit, and feces.

Blood Alcohol Concentration (BAC)

The percentage of alcohol that is in a person’s bloodstream is known as the Blood Alcohol Concentration (BAC). BAC is usually expressed as a percentage of ethanol that is present in the blood in units of mass of alcohol per volume. For most people, one ounce of alcohol will produce a .015% blood-alcohol concentration. This means someone with a .015% blood-alcohol level will have little to no alcohol in their bloodstream after 10 hours have passed. It’s important to note that the more you drink, the longer alcohol stays in the system.

Once a person’s blood-alcohol levels go above .05% to .055%, alcohol’s negative effects start to increase. So feelings of calm, happiness, and relaxation start to turn into depression, irritability, and disorientation. At around .08% to .09%, sense of balance is off and motor skills are impaired. Some people may also begin vomiting at this level due to excess alcohol in the blood and the body’s inability to metabolize the alcohol fast enough. In the United States, someone is considered to be legally intoxicated and prohibited from driving a vehicle if their BAC level is 0.08% or greater.

Factors That Affect the Rate That Alcohol Is Processed

Alcohol is metabolized at a constant rate, but some people may feel the effects of alcohol for longer amounts of time. That’s because blood alcohol concentrations can fluctuate among people for a variety of the following reasons:

Age

The older a person is, the longer alcohol stays in the liver before it moves into the general bloodstream or is metabolized – increasing length of intoxication and risk of damage to the liver. The amount of water in the body also goes down with age, contributing to a higher BAC. An older person is additionally more likely to be taking medication and this affects the liver as well. All of these factors mean that alcohol is processed by the body at a slower rate.

Biological Sex

Due to several physiological reasons, alcohol is metabolized differently by women than it is men and will stay in a woman’s system longer. This is largely due to the fact that women tend to have a higher percentage of body fat and lower percentage of body water compared to men. This means that a man’s body will automatically dilute the alcohol more than a woman’s, even if the two people are the same height and weigh the same amount. Hormone levels also affect the body’s ability to process alcohol, and women will experience higher BACs drinking alcohol right before menstruation. Studies have additionally shown that women have less acetaldehyde dehydrogenase, the enzyme used to metabolize alcohol in the stomach.

Food

Eating a meal and having food in the stomach prior to drinking can have a powerful influence on the absorption rate of alcohol. Food helps dilute the alcohol and slow the emptying of the stomach into the small intestine, where alcohol is rapidly absorbed. Peak BAC could be as much as 3 times higher in someone with an empty stomach than in someone who has consumed food before drinking. Eating regular meals and having snacks while drinking can help induce enzyme activity in the liver and slow the rate at which alcohol is absorbed.

Body Size

A person’s body size and composition are also factors that can impact how fast alcohol is processed. Low-water fatty tissue cannot absorb alcohol to the extent that high-water muscle tissue can, meaning individuals with more body fat generally have higher BAC. Correspondingly, an individual that is extremely muscular but of shorter stature will have a higher BAC than someone taller than them of the same composition.

Medications

Certain medications can interact with alcohol and alter the metabolism, thereby affecting how the body is able to process alcohol. Some medications slow the emptying from the stomach into the small intestine and liver, causing the alcohol to be rapidly absorbed. This results in higher BAC levels and intoxication that affects the body more quickly. Medications that are specifically known to interact with alcohol include:

• Anti-anxiety medications such as Xanax
• ADHD medications like Adderall
• Cough and cold medicines
• Diabetes medications such as Chlorpropamide

What Is A Standard Drink?

People often underestimate how much they have had to drink because they aren’t using standard drink measurements. One standard drink is equal to one 12-oz beer, 1.5 ounces of liquor (whiskey, vodka, etc.), or a 5-oz glass of wine.

Drink Responsibly And Safely

Understanding BAC and the rate that alcohol is metabolized by the system can help prevent the dangerous consequences of excessive alcohol consumption. However, if you’re someone who struggles to drink safely and in moderation, it may be time to seek professional help. Contact a treatment provider today to learn about rehabilitation options.