Effects of ethanol (0.75 g/kg body weight) on the activities of selected enzymes in sera of healthy young adults: 2. Interindividual variations in response of gamma-glutamyltransferase to repeated ethanol challenges.

We measured individual temporal changes in gamma-glutamyltransferase activity in serum after four consecutive ethanol challenges in each of eight apparently healthy volunteers. Each challenge consisted of ingesting 0.75 g of ethanol per kilogram of body weight on two evenings, followed by five days of abstention during which the activity was assessed at regular intervals. A nine-day abstention period preceded the study, and initial baseline activity was determined. The highest values for the group mean activity were +12%, +11%, +22%, and +18% greater than baseline after the first, second, third, and fourth ethanol challenges, respectively. We noted marked intra-individual and interindividual variation in the enzymic response; peak values ranged from +1% in one subject to +57% in another. The possible causes for these biological variations are discussed.