Aims: While serum gamma-glutamyltransferase (GGT) enzyme activity is a well established biomarker of excessive alcohol consumption and liver dysfunction, recent studies have also implicated it as a predictor of morbidity due to extrahepatic causes. Therefore, further information on the associations between ethanol intake and GGT activities in apparently healthy individuals appears warranted.
Methods: Data on alcohol consumption and serum GGT activities were collected from 18,899 individuals (8807 men, 10,092 women), mean age 48 years and range 25-74 years, who participated in a national cross-sectional health survey. Alcohol use was assessed by detailed questionnaires and the study population was subsequently divided into subgroups according to age and gender. Body mass index and smoking were used as covariates in all analyses.
Results: In men over 40 years, a reported regular consumption of 8 standard ethanol doses ('dose' = 12 g ethanol) or more per week was found to lead to a significant elevation in serum GGT activities, whereas those below 40 showed first significant changes not until the reported ethanol intake exceeded 14 doses per week. For women, the corresponding threshold levels were four and seven standard ethanol doses, respectively.
Conclusion: The data pertaining to the present population sample indicate that rather low levels of reported regular ethanol consumption lead to elevated levels of GGT and that age over 40 markedly enhances the impact of alcohol consumption on GGT activity. The present findings should form the basis for defining safe levels of ethanol consumption and in recalibrating goals for normal limits in the clinical use of GGT measurements.