Prevalence and etiology of elevated serum alanine aminotransferase level in an adult population in Taiwan

Background: The prevalence and etiologies of elevated alanine aminotransferase (ALT) have geographic variations and they are rarely reported in Taiwan. Through a population-based screening study, the prevalence and etiologies of elevated ALT in an adult population of Taiwan were assessed. Methods:A cross-sectional community study in a rural village of Taiwan was conducted in 3260 Chinese adults (age >= 18 years) undergoing ultrasonography (US), blood tests, and interviews with a structured questionnaire. The diagnostic criteria of non-alcoholic fatty liver disease (NAFLD) included alcohol intake < 20 g/week for women or < 30 g/week for men, negative hepatitis B virus (HBV) and hepatitis C virus (HCV) infections, no known etiologies of liver disease, and US consistent with fatty liver. Results:The prevalence of elevated ALT was 11.4% (372/3260). The probable cause of this elevation was excess alcohol consumption in 0.8%, HBV in 28.5%, HCV in 13.2%, both HBV and HCV in 2.2%, NAFLD in 33.6%, and unexplained cause in 21.8%. The etiologic distribution of elevated ALT was similar in both genders, although elevation was more common in men compared to women (17.3% vs 6.1%, P < 0.05). The prevalence of elevated ALT in NAFLD was 18.1% (125/691), and the positive predictive value was 33.6% (125/372). The development of NAFLD was related to increasing age (age between 40 years and 64 years, odds ratio [OR] 1.59, 95% confidence interval [CI]: 1.25-2.01; age >= 65 years, OR 1.46, 95%CI: 1.08-1.96), fasting plasma glucose (FPG) >= 126 mg/dL (OR 1.54, 95%CI: 1.11-2.14), bodymass index (BMI) >= 25 kg/m(2) (OR 5.01, 95%CI: 4.13-6.26), triglyceridemia >= 150 mg/dL (OR 1.96, 95%CI: 1.58-2.42), and hyperuricemia (OR 1.50, 95%CI: 1.22-1.84). Elevated ALT was related to male gender, BMI >= 25 kg/m(2), and triglyceridemia >= 150 mg/dL in subjects without known etiologies of liver disease (all P < 0.05). Conclusions:Non-alcoholic fatty liver disease appears to be the commonest cause of elevated ALT and presumed liver injury in Taiwan. The development of NAFLD is closely associated with many metabolic disorders. Metabolic disorders are also related to elevated ALT in subjects without known etiologies of liver disease.