Serum Hepatic Enzyme Activity and Alcohol Drinking Status in Relation to the Prevalence of Metabolic Syndrome in the General Japanese Population

BACKGROUND: Studies on the combined associations of elevated serum hepatic enzyme activity and alcohol drinking with metabolic syndrome are rare. Our objectives were to evaluate the associations of elevated serum hepatic enzyme activity with the prevalence of metabolic syndrome in the general Japanese population and whether alcohol drinking had a modifying effect on these associations. METHODS: We conducted a cross-sectional study with 1,027 men and 1,152 women throughout Japan during 2002–2010. Biochemical factors including alanine aminotransferase (ALT) and gamma-glutamyl transferase (GGT) were determined in overnight fasting blood, and a survey on lifestyle was conducted by questionnaire. Serum ALT and GGT levels were divided into tertiles in men and women, and their associations with the prevalence of metabolic syndrome were evaluated by logistic regressions. RESULTS: Elevated serum ALT and GGT, even within the reference range, were independently associated with increased metabolic syndrome prevalence and were associated with most of its components in both sexes, except for the association between GGT and low high-density lipoprotein (HDL) cholesterol in men. Stratified analyses by alcohol drinking status revealed that within the same tertile category of serum ALT and GGT, subjects classified as alcohol abstainers showed higher adjusted odds ratios for metabolic syndrome prevalence than those classified as regular alcohol drinkers in both sexes. The interaction effects of serum GGT with alcohol drinking status on metabolic syndrome prevalence were significant in both sexes. CONCLUSIONS: These results suggest that elevated serum ALT and GGT, even within the reference range, are independently associated with increased metabolic syndrome prevalence, especially in alcohol abstainers, in Japanese men and women.