Heavy drinking among Norwegian male drunken drivers: a study of gamma-glutamyltransferase.

The distributions of blood alcohol concentrations (BACs) of different age groups of drunken drivers suggested that a large number of the drunken drivers above 29 years of age had high tolerance to alcohol, and many of these might be heavy drinkers. In order to study the extent of heavy drinking, gamma-glutamyltransferase (GGT) activities were measured in 269 blood samples from male drunken drivers using a new method suitable for hemolyzed blood samples. Of the drunken drivers above 29 years of age, 40% had elevated GGT activities, indicating that roughly one-third of these drivers might be heavy drinkers (consuming more than 80 g of alcohol/day). Of the drunken drivers above 29 years of age with BACs above 55 mmol/liter (250 mg/100 ml), 63% had elevated GGT, indicating that a large majority of these drivers were heavy drinkers. Fewer of the younger drivers had elevated GGT activities. The GGT activities of the repeating offenders indicated that the percentage of heavy drinkers in this group was approximately the same as in the total population of apprehended drunken drivers.