In addition to direct questioning of patients, biochemical markers may indicate drinking problems. The unique advantage of biomarkers is that they can not be feigned. They may confirm or bring into question an individual’s own report of alcohol use explained John Allen, Associate Director of Treatment Studies at the National Institute on Alcohol Abuse and Alcoholism. In particular, they can help primary care physicians in screening for heavy drinking. Patients who come up positive on the tests may then be given a more in depth diagnostic evaluation. These lab tests may also assist in identifying individuals in alcohol treatment who have relapsed to drinking. Knowing that the patient has relapsed can signal the need to modify or intensify his or her treatment program. Dr. Allen added that some people in treatment might be too embarrassed to let the clinician or counselor know they had started drinking again, fearing to disappoint them. This study is in the April issue of Alcoholism: Clinical & Experimental Research.
"Another use for biomarkers involves insurance companies," observed Martin Javors, professor of psychiatry at the University of Texas Health Science Center, San Antonio. "Also, physicians may want to be sure that people who are going to get liver transplants are not drinking." Javors speculated that courts might also be able to use biomarkers in DWI or probation cases, dependent upon future refinement of biomarkers’ alcohol detection capabilities.
The ratio of men who have alcohol problems versus women is roughly three to one, yet women who drink too much seem to be at increased risk for certain negative consequences. "Although alcohol problems in women are less frequent," agreed Allen, "they are clearly no less serious when they do occur. In fact, women are more liable than men to certain types of alcohol-related damage, such as liver disease."
Allen and his co-authors reviewed 16 alcohol-screening studies from 1988 to 1999 that utilized three promising biochemical markers for excessive drinking or alcohol dependence in women: gamma glutamyl transferase (GGT), carbohydrate-deficient transferrin (CDT), and mean corpuscular volume (MCV). While GGT and CDT appear to be somewhat less sensitive in women than in men, they do provide useful clinical information, especially when they are used in combination.
GGT, the most widely used biochemical marker of alcohol consumption, is an enzyme found in the kidney, liver, pancreas, and prostate gland. It is a general marker of liver damage and, to the extent that liver damage is often associated with heavy use of alcohol, can serve as a helpful indicator of alcohol misuse. CDT is a more recently discovered biomarker of heavy drinking. (Transferrin is a protein synthesized and secreted by the liver and transfers iron around the body.) MCV - a lesser-known biochemical screen for problematic drinking - is a measure of red blood cell size.
As a director of a clinical laboratory in a large city, Javors calls the report’s findings "clear and timely." Although he is optimistic about future uses of MCV, he is more immediately concerned about the potential applications of CDT, recently approved by the Federal Drug Administration for measuring heavy alcohol consumption. "We will begin offering this test in our lab within the next few months," he said.
Javors noted that future research could go in several different directions. "Not enough studies have been done to compare the value of these markers for the detection of binge drinking versus daily drinking. It is likely that binge drinking may be more difficult to detect. A lot of studies on the effectiveness of biochemical markers have been done on the basis of reported drinking."
He laughed. "Here we’re trying to develop a marker to independently determine if someone is drinking, and what are we using as the independent variable? Self reporting." In order to address potential inaccuracies that may result from self-reporting, Javors said he and his team have "started a study in animals to precisely evaluate the kinetics of these markers and to compare continuous or daily ethanol intake with discontinuous or binge ethanol intake on their levels in serum."
Funding for this Addiction Science Made Easy project is provided by the Addiction Technology Transfer Center National Office, under the cooperative agreement from the Center for Substance Abuse Treatment of SAMHSA.
Articles were written based on the following published research:
Allen, J.P., Litten, R.Z., Fertig, J.B., & Sillanaukee, P. (2000, April). Carbohydrate deficient transferrin, gamma glutamyl transferase and macrocytic volume as biomarkers of alcohol problems in women. Alcoholism: Clinical and Experimental Research, 24(4), 492-496.