Higher serum free glycerol levels in a group of alcoholics than in controls

Background The biomarkers of excessive alcohol intake reported thus far have not always been reliable. We discovered the presence of free glycerol (FG) by high-performance liquid chromatography (HPLC) in the serum of alcoholic patients but not in healthy persons, and a higher percentage of the alcoholics were positive for serum FG than for gamma-glutamyl transpeptidase, mean corpuscular volume, or carbohydrate-deficient transferrin (%CDT). Therefore, in this study, we investigated whether the same results as with HPLC could be obtained by measuring FG with an easy-to-use autoanalyzer and whether the serum FG measured by this method would be useful as a biomarker of excessive alcohol intake. Methods First, the measurements of serum FG made by HPLC and by a biochemical method with an autoanalyzer were tested for a correlation, and then fasting serum FG was measured with the autoanalyzer in 3 groups: a group of Japanese male alcoholics who drank until just before admission, a group of Japanese male patients with chronic viral hepatitis, and a group of Japanese healthy male volunteers. Results There was a strong positive correlation between the serum FG values measured by HPLC and by the autoanalyzer in the alcoholic group. The values in the alcoholic group were significantly higher than in the viral hepatitis group and healthy control group. We set the cutoff serum FG value for discriminating between the alcoholic group and the other 2 groups in the receiver operating characteristic analysis at 0.9 mg/dl, and that cutoff value provided a sensitivity of 80% for identifying the alcoholic group and a specificity of 84 and 94% in relation to the viral hepatitis group and the healthy volunteer group, respectively. Among various clinical tests in the alcoholic group, serum FG showed the highest rate of abnormally high value. Conclusions Measurement of serum FG with an autoanalyzer may be useful as a biomarker of excessive alcohol intake.