Biochemical diagnosis of alcoholism. A test of the discriminating capabilities of gamma-glutamyl transpeptidase and mean corpuscular volume.

Quadratic discriminant analysis was conducted between 121 medically documented male alcoholics who presented for treatment and 130 male nonalcoholic outpatients who were concerned about the possibility of venereal disease. Analysis of gamma-glutamyl transpeptidase (GGT) and mean corpuscular volume (MCV) resulted in correct classification of 94% of nonalcoholics but only 36% of alcoholics. In contrast, analysis of 24 commonly ordered clinical laboratory tests produced correct classification of 100% of nonalcoholics and 98% of alcoholics. Transforming the laboratory-determined values to a normal-abnormal dichotomy on the basis of reference values improved the classification accuracy of GGT and MCV to 77%. However, consideration of ten of the other tests resulted in an accuracy of 98% for alcoholics and 95% for nonalcoholics.