Distribution and population determinants of gamma-glutamyltransferase in a random sample of Sardinian inhabitants

The relation of a number of determinants to serum gamma-glutamyltransferase (GGT)was studied in a random sample of Sardinian inhabitants of 2283 males and 2520 females aged 20-59 years. The aim of the study was to assess the influence of environmental, behavioural and biochemical factors on GGT levels. Mean values were higher in males than in females and increased with age in both sexes. In sex-specific multiple regression analysis, GGT showed a positive association with body mass index (BMI), alcohol use, total serum cholesterol (T-C), HDL cholesterol (HDL-C), triglycerides (TG), apolipoprotein B (ApoB) and age, and a negative one with coffee consumption and physical activity in males, while in females the enzyme was positively associated with BMI, alcohol use, age, T-C, ApoB, TG and cigarette smoking. The negative association between coffee drinking and serum GGT observed in males suggests that coffee may inhibit the inducing effects of other factors, particularly alcohol use, on GGT in the liver. No biological mechanism has been suggested to explain the association of GGT with BMI, age or physical activity. This study confirms the importance of GGT as a strong marker for alcohol use; but a number of variables, ranging from life-style to biological characteristics, are also important determinants of its plasma values in the 'normal' population.