Serum gamma-glutamyl transferase in alcoholics, moderate drinkers and abstainers:: Effect on GT reference intervals at population level

Aims: To clarify in the association between amount of ethanol consumption and serum gamma-glutamyl transferase (GT) levels. Methods: GT values were measured from 195 individuals with a wide variety of well-documented ethanol consumption assessed by detailed personal interviews using a time-line follow-back technique. These included 103 heavy drinkers (90 men, 13 women) and 92 healthy volunteers (54 men, 38 women) who were either abstainers (n = 30) or moderate drinkers (n = 62). For comparisons, data were collected from GT measurements for establishing GT reference intervals from 2485 healthy volunteers including 1156 abstainers and 1329 moderate drinkers. Results: GT values in the individuals whose mean ethanol consumption exceeded 40 g of ethanol per day were significantly higher than those in the moderate drinkers with a mean consumption of 1-40 g/day (P < 0.001) or in abstainers (P < 0.001). The GT values in the group of moderate drinkers also exceeded those of the abstainers (P < 0.001). The upper normal GT limits obtained from the data from abstainers were markedly lower (men 45 U/l, women 35 U/l) than those obtained from the population of moderate drinkers (men 66 U/l, women 40 U/l). Conclusions: Serum GT concentrations may respond to relatively low levels of ethanol consumption, which should be considered when defining GT reference intervals. The continuous increase in alcohol consumption at population level may lead to increased GT cut-off limits and hamper the detection of alcohol problems and liver affection in their early phase.