Alanine Aminotransferase within Reference Range Is Associated with Metabolic Syndrome in Middle-Aged and Elderly Chinese Men and Women

Objective: To investigate the association between serum ALT level within reference range (≤40 U/L) and morbidity of MetS in a large middle-aged and elderly Chinese community population. Methods: Our study was a community-based cross-sectional survey which used cluster sampling method. From November 2011 to August 2012 a total of 16,539 subjects (males 5184; females 11,355) with serum ALT levels in the normal range aged ≥40 years from Shijingshan District (Beijing, China) were included in the study. Data on demographic information, lifestyle, history of diabetes mellitus, hypertension, dyslipidemia and liver disease were collected. Body height, body weight, waist circumference, hip circumference, and blood pressure were recorded. The oral glucose tolerance test or a standard meal test and blood lipid test was performed. The determination of metabolic syndrome was according to the unified criteria published in 2009. The association between serum ALT level and metabolic syndrome was evaluated by logistic regression. The association between serum ALT level and all components of metabolic syndrome was evaluated by multiple linear regression. p < 0.05 was regarded as statistically significant. Results: The prevalence of metabolic syndrome was 41.4% in males and 40.6% in females. We found ALT level was positively associated with odds of metabolic syndrome after adjustment for age, smoking, and alcohol intake. The odds ratio values of MetS in the ALT quartiles 2–4 groups were 1.920 (95%CI: 1.619–2.277), 2.853 (95%CI: 2.407–3.381), and 4.171 (95%CI: 3.510–4.956) in males; 1.889 (95%CI: 1.671–2.136), 3.490 (95%CI: 3.095–3.935), and 5.593 (95%CI: 4.957–6.311) in females, respectively, compared with the ALT quartile 1 group. Conclusions: Higher serum ALT level within the reference range was associated with increased odds of MetS in middle-aged and elderly Chinese men and women.