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Research Summary

Combining GGT and CDT to Detect Unhealthy Alcohol Use

No single serum test can effectively detect unhealthy alcohol use. Combining tests, however, may improve detection. Researchers compared the performance of a combined index of gamma-glutamyltransferase (GGT) and carbohydrate-deficient transferrin (CDT) (GGT-CDT) with other biomarkers in 3 groups: 165 heavy drinkers* with alcohol dependence, 51 moderate drinkers, and 35 abstainers. Of the heavy drinkers, 51 had evidence of liver disease but not hepatitis B or C, and 44 were later assessed during supervised abstinence.

  • The sensitivity of GGT-CDT for detecting heavy drinking was 90% (specificity 98%) and exceeded that of the other biomarkers: 63% for CDT alone; 58% for GGT alone; 50% for alanine aminotransferase; 47% for aspartate aminotransferase; and 45% for mean corpuscular volume. The superior performance of GGT-CDT was not affected by the presence of liver disease.
  • During a mean of 11 days of supervised abstinence, 93% of supervised subjects had a decrease in GGT-CDT of 1.5% of the initial value per day.


This study suggests that combining biomarkers may be more fruitful than individual serum tests for detecting heavy drinking. Still, many questions remain about using combined biomarkers in clinical settings where the distinctions among drinking groups will not be as clear as in this study.

Jeffrey H. Samet, MD, MA, MPH
*Drank approximately 3–40 drinks per day


Hietala J, Koivisto H, Anttila P, et al. Comparison of the combined marker GGT-CDT and the conventional laboratory markers of alcohol abuse in heavy drinkers, moderate drinkers and abstainers. Alcohol Alcohol. Advance Access published on June 23, 2006; doi:10.1093/alcalc/agl050.