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Postal service updates: October - December

Carbohydrate Deficient Transferrin (CDT) DVLA Blood Test

Carbohydrate Deficient Transferrin (CDT) DVLA Blood Test


Carbohydrate Deficient Transferrin (CDT) is a biomarker for heavy alcohol consumption and is used by the DVLA in its fitness-to-drive test for high risk offenders. Please note: 2% of people will not be able to get a result from this test due to having a harmless genetic variant of the transferrin protein in their body.
Blood sample 1 biomarker included Results estimated in 7 working days from sample receipt at lab
Carbohydrate Deficient Transferrin (CDT) DVLA Blood Test
Carbohydrate Deficient Transferrin (CDT) DVLA Blood Test
Carbohydrate Deficient Transferrin (CDT) DVLA Blood Test
Carbohydrate Deficient Transferrin (CDT) DVLA Blood Test

Is it for you?

Have you lost your driver’s licence as a result of problem drinking but worked hard to maintain consistent changes in your lifestyle and are no longer drinking heavily/frequently binge drinking? You may be looking for evidence that your problem drinking is in the past, and relapse has not occurred. This test could provide you with the reassurance you would pass the DVLA fitness-to-drive test and be one step closer to regaining your licence.
Please note: This test is analysed using a different method from the official DVLA laboratory. It will not be possible to get a result for around 2% of people taking this test due to a normal genetic variant in transferrin, which is a protein produced by the liver. In this situation, an alternative test will be recommended.

What's included?

Biomarker profile

  • Alcohol Consumption

Alcohol Consumption (1 Biomarker)

From the expert

The Carbohydrate Deficient Transferrin (CDT) test measures a particularly sensitive biomarker that tracks heavy alcohol consumption over an extended period of time. Transferrin is a protein which carries iron to parts of the body that need it. Drinking too much alcohol can cause an increase in certain types of transferrin which are deficient in carbohydrate. If an individual drinks steadily and heavily (4-6 units of alcohol per day) for several weeks the percentage of transferrin which is deficient in carbohydrate will rise. The longer a person drinks at this level, the higher the level of CDT.

Intermittent or binge drinking can also increase CDT levels. The extent to which this occurs is dependent on the frequency of binges and the amount of alcohol consumed on each occasion. Elevated CDT will decline with reduced alcohol consumption and will revert to normal after several weeks of abstinence.

This test has a very high level of specificity (i.e. it is not affected by other drugs or substances) and therefore it has been adopted by the Secretary of State's Honorary Medical Advisory Panel as the sole test for assessing harmful use of alcohol for high risk offenders.

Whilst this test is considered to be the gold standard means for assessing harmful alcohol use, results will not be able to be processed for 2% of the population who have a harmless genetic variant of the transferrin protein, which causes it to have a different shape. On processing the results, our lab will identify customers who fall into this rare category. These customers will be advised to take the Phosphatidylethanol Blood Test.

Dr Sam Rodgers MBBS, MRCGP
Chief Medical Officer

Why take this test?

  • You have received a driving ban and are reapplying for your license from the DVLA
  • You want to make sure that you will pass the DVLA medical
  • You want to use this test as proof that you have stopped or reduced your alcohol consumption
  • You've been asked by your medical practitioner to take this test

Laboratories you can trust

Trusted by the NHS and private clinics alike, you can be sure of the highest testing standards from our UKAS accredited partner laboratories.

Dr Sam Rodgers - Chief Medical Officer

Expert advice with your results

Get trusted advice and comments from one of our doctors based on your results.

Your personal health centre

Your personal health centre

Discover the easy way to track your health through our online portal, View your results with doctor's advice, monitor any changes over time and see the improvements you can make to your health with simple lifestyle changes.

Questions? Let us help
Questions? Let us help

Questions? Let us help

Our customer care team is on-hand to help you find the test that's right for you. Get in touch via phone, live chat or email.


Our tests are not a substitute for seeing your doctor, especially if you are suffering symptoms. Our doctors will interpret your results based on the information you have provided, but will not diagnose, consult or provide any treatment. You will be advised to see your doctor for any necessary follow-up action.