A blood alcohol test can be used to measure the level of alcohol in an individual’s blood. As well as blood alcohol tests, urine alcohol tests, breathalysers, nail clippings and hair samples can also be used to measure the level of alcohol in someone’s system.

The reason for this is that when alcohol is consumed, it is absorbed into the bloodstream and most of it (around 90%) is broken down in the liver. The rest of the alcohol is passed out of the body in exhaled breath and urine (hence the urine and breath tests, but these tests need to be performed within 24–48 hours).

It takes the liver on average about 1 hour to break down 1 unit of alcohol. If someone has been drinking excessively, and over an extended period of time, the effects on the liver and other cells in the body can be measured by analysing alcohol biomarkers that circulate in the blood. It is these alcohol biomarkers that can also be measured in nail clippings and hair samples.

AlphaBiolabs is able to perform four blood alcohol tests, which measure biomarkers. For all of these tests, the window of detection is around 4 weeks.

  • Liver function test (LFT)
  • Carbohydrate deficient transferrin (CDT)
  • Mean corpuscular volume (MCV)
  • Phosphatidylethanol (PEth)  

Liver function test LFT

As the liver is the organ responsible for breaking down 90% of alcohol consumed, an individual who consumes excessive amounts of alcohol will damage this organ. As a result, they may experience decreased liver function. A liver function test (LFT) therefore measures the effects of alcohol on five enzymes in the blood that are produced by the liver. Abnormal results can indicate a problem with the liver. For example, an elevated aspartate aminotransferase (AST) value is a biochemical indicator of possible alcohol abuse.

The panel of markers tested include total bilirubin, aspartate transferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP) and gamma glutamyl transferase (GGT) to ensure the result is as accurate as possible.

Carbohydrate deficient transferrin CDT

Transferrin is a protein largely made in the liver that regulates an individual’s iron absorption into the blood. It attaches iron molecules and transports them to the bone marrow, spleen and liver. An individual who consumes excessive amounts of alcohol increases certain types of transferrin that are carbohydrate-deficient. When carbohydrate-deficient transferrin (CDT) increases, it can be measured in the bloodstream and is therefore a biomarker of alcohol abuse.

Mean corpuscular volume MCV

Heavy drinking over longer period of time damages the bone marrow where red blood cells are produced. The effect is that the red blood cells develop abnormally and become large. As a result, the mean corpuscular volume (MCV) index becomes higher than normal, which persists as long as drinking of alcohol continues.

Phosphatidylethanol PEth

Phosphatidylethanol (PEth) is a direct biomarker of alcohol that can only be detected when alcohol has been consumed. This makes it a highly reliable blood test for alcohol abuse. PEth testing can detect chronic and single-drinking episodes. It can also be used to monitor abstinence, drinking behaviour and identify relapse. PEth analysis can also verify whether an individual has changed their pattern of alcohol consumption.

PEth alcohol testing provides high specificity (48–89%) and sensitivity of 88–100%  because it is directly related to alcohol consumption.

Order a blood alcohol test

As well as blood alcohol tests, AlphaBiolabs offers other alcohol testing solutions including instant breath tests, nail clippings body hair and 3- or 6-month hair strand testing to show alcohol consumption over a period of time. Real-time results are also available with SCRAM Continuous Alcohol Monitoring®. For expert advice, please call Customer Services on 0333 600 1300 or email us at