Alcoholism: Carbohydrate Deficient Transferrin Test – Part 2

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Alcoholism: Carbohydrate-Deficient Transferrin Test – Part 2




Guest:  Dr. Ray Anton – Psychiatry & Behavioral Sciences

Host:  Dr. Linda Austin – Psychiatry


Dr. Linda Austin:  I’m Dr. Linda Austin.  I’m interviewing Dr. Ray Anton who is distinguished university Professor of Psychiatry in the behavioral sciences, and this is part two of a two-part podcast series about a marker for alcohol abuse, which is CDT, or carbohydrate-deficient transferrin.  Dr. Anton, in this podcast, I really want to focus on the clinical uses and usefulness of this test.  A basic question, first, how much does it cost and how widely available is it?


Dr. Ray Anton:  Well, those are two very important questions that the listener may have.  First of all, the availability isn’t wide.  We have one of probably only handful of laboratories in the country that actually perform CDT testing.  But the major laboratories in the country, like LabCorp and Quest, and others, have a mechanism that they either do it themselves or refer them to reference labs, like our lab here at the Medical University of South Carolina. 


The cost varies depending on where you have it done and whether there are intermediaries or not.  As in most of medicine, there is no standard for these sorts of things.  But, typically, if one was to go into a commercial lab where they would have to send it to a reference lab to have it done, it would cost somewhere between $100 and $150.  Our lab, at the medical university here, does it for clinical patients for about $75, and under contract with large healthcare entities or for clinical trials.  But we can oftentimes do it for less because we do it in large volume and in batches.  That’s a long answer to the question.


Dr. Linda Austin:  What are some of the clinical settings or scenarios in which physicians order this test?


Dr. Ray Anton:  Well, it ranges quite a bit, and it’s actually somewhat illustrative of the types of issues that are involved in healthcare with people that drink heavily.  So it ranges all the way from primary care, where a primary care physician may be wanting to evaluate the role of heavy drinking in a person’s hypertension, for instance, or in their diabetes control, or in digestive disorder diseases, all of which alcohol may play a role in the underlying etiology, cause or treatment of the disease through trauma surgeons who see quite a bit of alcohol-related trauma, all the way from car accidents to fires, to domestic violence and assaults, all of which have a considerable amount of alcohol use involved with them. 


And those patients are particularly vulnerable to acute problems, either from alcohol withdrawal or delirium tremens.  But also, heavy alcohol use can cause bleeding problems and an increase in infections.  And so the surgeons really want to know what the person’s drinking history is so they can treat them better.


And then the other major use is an addiction specialist where a person is being treated for alcohol problems and you want to monitor them over time.  It can range all the way from the impaired professional, where you want to have the highest degree of certainty that a doctor, nurse, a lawyer, a pilot is not using alcohol, and you want an objective blood test to help in ascertaining that, all the way through treating people who are coming in for treatment. 


What we’ve found is that patients respond very well to having an objective test.  First of all, if the CDT which was elevated when they first came, due to the heavy drinking, goes down, it reinforces to them how well they’re doing in reducing their drinking or maintaining abstinence.  It also may be an indication of other improvements in healthcare parameters, like hypertension, which is also affected by alcohol.


But, our clinicians also like them because when the value goes back up and a patient doesn’t necessarily admit to either any alcohol use or significant alcohol use, one can point to the test and open up a more valid and objective dialogue about what might be actually happening.  And we’ve seen, on a number of occasions, where a patient, when confronted with the evidence, more or less, says, well, doc, you know, maybe I have been drinking a little bit more, or maybe those drinks that I thought I was having were a little bit bigger than I really told you about.  It allows the doctor to say, well, okay, let’s see how we can do better and what might be in your way of doing better, may be driving you to drink.  It just improves the quality of care.  So, our clinicians have generally found that it’s a much more positive experience than one might expect initially in getting blood tests on people with alcohol problems.


Dr. Linda Austin:  I would imagine that some potentially complex and very interesting legal situations could arise, let’s say a DUI.  The surgeon has drawn a CDT level and determined that the patient was chronically alcoholic which might put that patient in a different legal situation.  Do you hear about those sorts of issues?


Dr. Ray Anton:  Well, that’s a good question, and is actually a concern that’s very acute right now as we start using these tests in various medical settings.  I will say two things about your question specifically.  An elevated CDT does not make a diagnosis of alcohol use disorders, either alcohol abuse or alcoholism, because you can be a heavy drinker and not meet the criteria for alcoholism and still have an elevated CDT test.  So, alcohol dependence or abuse is a clinical diagnosis, and the lab test does not make a clinical diagnosis. 


Second of all, an elevated CDT indicates heavy drinking in the recent past, but doesn’t necessarily mean that somebody was intoxicated at the time of an accident or trauma.  That would be an inference, which is not supported by the test itself.  The trauma surgeons have felt that to be useful.  But how it actually winds up being reflected in patient care and in legal situations will need to be worked out in the future.  I can say that in Europe, there are a number of countries that actually use CDT for an indication of when somebody can get their license back.  Some Scandinavian countries, I think, France, Germany, perhaps, and certain areas, require CDT levels to be normal for, say, six months or a year, along with clinical reports, in order for somebody to get their license back once it was taken away because of driving under the influence.  So it is being used in legal systems around the world.


Dr. Linda Austin:  You had mentioned previously that about 30 to 40 percent of people will not have an elevated CDT, despite heavy drinking.  Is there any particular racial group that is more or less likely to have that marker or not?


Dr. Ray Anton:  No.  There’s no indication that a race or ethnic-based difference underlies people’s sensitivity to have the elevation in CDT.  Originally, it was thought that females had a higher level of CDT than males.  But once the CDT is corrected for the total amount of transferrin present, which is the normal protein, that gender difference seems to go away.  However, even with that corrective factor, there may still be a slight difference.  The problem is that it’s hard to sort out because women, first of all, oftentimes don’t drink as much as men, on average, even when they’re drinking heavily.  And because of their difference in body water and body mass index, weight, basically, they can have different blood alcohol levels than men for the same amount of alcohol consumed.  So it gets to be a very complicated process to try to determine how much of it is what they’re drinking and how much of it is gender.


Dr. Linda Austin:  Dr. Anton, thank you so much for talking with us today.


Dr. Ray Anton:  Thank you very much.


If you have any questions about the services or programs offered at the Medical University of South Carolina or if you would like to schedule an appointment with one of our physicians, please call MUSC Health Connection:  (843) 792-1414.

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