Carbohydrate Deficient Transferrin
Current available data indicates that consumption of 50-80 g/day of alcohol for at least one month is required to produce an abnormal CDT level. However it has been our experience of many CDT results allied to observations, questions and interviews that at the lower level of consumption there are a number of anomalies that have not yet been shown in any scientific studies. Everyone has an individual normal level of production of CDT and this is measured as a percentage of the level of Transferrin produced by the liver. (Transferrin is the protein which transfers iron to various parts of the body). Transferrin has molecular Carbohydrate side chains which can be “knocked off” by alcohol, hence the name Carbohydrate Deficient Transferrin. This will increase the percentage of CDT and the greater the increase, the greater the amount of alcohol being consumed in most cases.
CDT has a half life of 14 days, which means that of the CDT produced today, only half will remain in the blood in 14 days time. If alcohol consumption is stopped, the level of CDT will return to its normal level for that person. The time it takes to do this is dependent upon the level on the day on which they stopped drinking. (i.e. the more they had been drinking the longer it will take to reach the normal level.) We also know that the body “learns” how to produce CDT. This means that someone who was previously a heavy drinker, stops drinking and then starts again will more quickly produce raised levels of CDT. Multiple blood tests (normally 3 in a six week period) is a very good method of determining whether a person who claims to have stopped drinking has in fact done so but should not be taken as predicting whether they will start again or not. This falls into the area of treatment of which there are many variations. (Please refer to our full paper on the above).
Blood Testing
We also offer a Blood testing service. An alcohol screening measures a number of markers in the blood to detect donors drinking habits. This test can be used alone or in conjunction with the alcohol in hair analysis. Alcohol is quickly metabolised by the liver and passed from the body. Research for over 60 years has therefore been concentrated upon trying to determine the effect of alcohol consumption upon enzymes naturally produced by the liver.
The enzymes in question are:
1. GGT (Gamma-Glutamyltransferase)
2. AST (Aspartate Transaminase)
3. ALT (Alimine Transaminase)
4. CDT (Carbohydrate-Deficient Transferrin)
5. In addition we calculate a marker which combines the measurements of GGT and CDT (GGT-CDT)
Also it is known that alcohol consumption can have an effect upon the MCV (Mean Corpuscular Volume- the size of blood cells). The liver enzymes the GGT-CDT and the MCV are known collectively as Markers for alcohol consumption. The major problems associated with these markers are:
1. The liver enzymes are all produced naturally by the body, within a “normal” range which can be quite wide.
2. The production of Enzymes outside of this normal range can be affected by reasons other than alcohol consumption. Studies of the effect of alcohol consumption upon these enzymes therefore come with 2 scientific terms attached i.e. Sensitivity and Specificity. A layman’s definition of these terms is given below.
3. The rates at which these markers return to the normal range vary It is with this in mind that we believe an interpretation of these markers needs to be evaluated by a psychiatrist specialising in this field.
Enzyme Activity
Heavy drinking damages the liver and Liver Function Tests will be abnormal if there is severe damage from drinking alcohol consistently over a long period, i.e. years. Liver Function Tests may also be abnormal if there has been binge drinking of say 2 weeks, followed by relative abstinence, or reduction in consumption. These enzyme levels return quite quickly to normal levels unless permanent liver damage has been sustained (e.g. cirrhosis) when the person abstains from alcohol. MCV The size of the red blood corpuscles (MCV) in the body may give an indication of prolonged heavy drinking; they can increase in size in these circumstances (40% of heavy drinkers). It takes a few months for them to return to normal after heavy drinking but they will normally do so.
For more details on CDT Testing, call Atkinson Lewis on 01792 578623.
