Updated 21 September 2015

Alcohol blood test

Alcohol is the most frequently abused drug worldwide.


Alcohol is the most frequently abused drug worldwide and health problems associated with the excessive intake thereof are on the increase. Current statistics indicate that 20-30% of all hospital admissions and healthcare cost are related to alcohol abuse. Therefore, a high priority should be given to strategies reducing the prevalence of alcohol abuse and dependency, by means of more effective diagnosis and early intervention.

Although there are several markers available to assess the likelihood of alcohol abuse, none of them are very specific and each has its limitations.

The recommended safe limits of alcohol intake are 21 units/ week for men and 14 units/ week for women.


  • 450 ml can beer 1,5 units
  • 750 ml wine 7-10 units
  • Bottle spirits 30 units

35% of men and 22% of women drink more than the above recommended limits.

What are biomarkers of alcohol abuse and/dependency?

These are markers/substances that can be measured in bodily fluid, for example blood, which give an indication of whether or not a person uses alcohol excessively. It is especially helpful in establishing the likelihood of alcohol use in the case of the person denying it.

Alternative name

Ethanol (Alcohol)

What are these markers?

There are many conventional biomarkers and a few possible new markers that can be measured.

  1. Alcohol levels

Measurement of alcohol levels from blood, breath or urine is normally used for patients with suspected alcohol intoxication.

  1. Gamma-glutamyltransferase (GGT)

GGT is the most widely used index of excessive alcohol intake. It is an enzyme that is produced by the liver. Chronic alcohol consumption is known to induce a rise in the blood level of GGT.

  1. Mean corpuscular volume (MCV)

The size of the red blood cells is often used as part of the screening of alcohol abuse. The larger the size of the red blood cell, the higher the likelihood of alcohol abuse.

  1. Other markers
  • Carbohydrate-deficient Transferrin (CDT)
    • New marker, highly specific for alcohol abuse
  • Liver enzymes
    • Aspartate aminotransferase (AST)
    • Alanine aminotransferase (ALT)
      • A ratio of AST to ALT over two is suggestive of alcohol abuse

How is the procedure performed?

All (except the breath and urine alcohol), is measured in blood. The person being investigated gives blood by means of a venipuncture (needle prick of a vein), usually on the inside of the elbow. The skin is first cleaned with an alcohol swab. (When collecting blood for blood alcohol levels, the skin should not be cleaned with an alcohol swab because it may falsely influence the results). You might experience a sharp pain, that feels like an insect bite where the needle enters the skin. Blood is collected in special tubes and sent off to the laboratory for analysis.


The risks include:

  • Pain at blood collection site.
  • Bleeding from the site where blood was collected, especially in patients on medication to thin the blood such as aspirin and warfarin. Always inform your doctor if you have a bleeding tendency or if you are on any medication.
  • Bruising.
  • Very seldom infection. Contact your nearest doctor or medical service if you experience any ongoing symptoms e.g. pain, redness, swelling at the collection site.


  1. Blood alcohol

Blood alcohol has a short half-life and is metabolised from the system relatively fast and the measurement is therefore time-limited.

  1. Gamma-glutamyltransferase (GGT)

GGT is age-dependent and increases with age. It is also less specific for alcohol abuse in certain medical conditions such as diabetes, and when the patient is taking certain medications (drugs for epilepsy).

  1. Mean corpuscular volume (MCV)

Less specific for alcohol abuse in patients with conditions that can influence the red cell size, for example vitamin B 12 and folate deficiencies, liver disease, underactive thyroid disease and smoking.

  1. Carbohydrate-deficient Transferrin (CDT)

Not widely available. May be influenced by genetic differences in transferrin.

Newer markers, including genetic markers for identifying individuals at risk of alcohol dependence are emerging.


Read Health24’s Comments Policy

Comment on this story
Comments have been closed for this article.

Live healthier

Exercise benefits for seniors »

Working out in the concrete jungle Even a little exercise may help prevent dementia Here’s an unexpected way to boost your memory: running

Seniors who exercise recover more quickly from injury or illness

When sedentary older adults got into an exercise routine, it curbed their risk of suffering a disabling injury or illness and helped them recover if anything did happen to them.