Independent association between low serum amylase and non-alcoholic fatty liver disease in asymptomatic adults: a cross-sectional observational study

Objectives: Low serum amylase (LSA) was reported to be associated with obesity, metabolic syndrome (MetS) and diabetes. However, it is unknown as to whether LSA is associated with non-alcoholic fatty liver disease (NAFLD), a hepatic manifestation of MetS and insulin resistance. Therefore, we performed a clinical epidemiological study to investigate this potential association. Design: A cross-sectional observational study with multivariate analysis. Setting: Subjects were recruited in a healthcare centre in Saitama, an eastern district of Japan, near Tokyo. Participants: A total of 1475 asymptomatic adults aged 30-79 years who underwent detailed medical check-ups and who regularly consumed small amounts of alcohol (<20 g/day). Outcome measures: Serum amylase, cardiometabolic risk factors, NAFLD determined by ultrasound, MetS determined by Adult Treatment Panel-III criteria and diabetes were assessed. Results: The prevalence of NAFLD increased significantly from 22.5% to 42.4% (all grades) and from 9.2% to 24.0% (moderate or severe grade) from the highest to the lowest quartile of serum amylase. Multiple logistic regression analysis showed that, compared with the highest quartile of serum amylase, the lowest quartile of serum amylase was significantly associated with any-grade NAFLD and with moderate-to-severe NAFLD, even after adjusting for MetS or diabetes. The association between LSA and any-grade NAFLD disappeared after further adjustment for body mass index or waist circumference, whereas the association between LSA and moderate or severe NAFLD remained statistically significant (ORs (95% CI), 2.01 (1.07 to 3.78) and 2.06 (1.09 to 3.87), respectively, both p=0.01). Conclusions: Our results suggest that LSA may be associated with moderate or severe NAFLD in asymptomatic adults independent of MetS, diabetes and obesity. These results warrant confirmation in further studies.