2977 Mercury Exposure and Risk of Non-Alcoholic Fatty Liver Disease and Advanced Fibrosis: Findings From the 2011-2016 National Health and Nutrition Examination Survey

Abstract

INTRODUCTION: Mercury (Hg) is a well-known toxic metal that is most commonly found in diet (seafood, rice), and other sources such as dental amalgams and batteries. The pathogenesis for hepatoxicity is theorized to be triggered by oxidative stress. We aim to investigate the association of Mercury with key demographic and clinical factors, as well as NAFLD and Advanced Fibrosis. METHODS: A population of 5,590 non-pregnant individuals age 18-74 were included in this secondary analysis of NHANES 2011-2016. Exclusion criteria: AST/ALT >500 IU/L, alcohol >10 drinks/week (females)/>20 drinks/week (males), transferrin saturation >50%, positive hepatitis B and C serology. NAFLD was defined by Fatty Liver Index score >60. Advanced fibrosis was defined by National Fibrosis Score >0.676. Student's T-test was used for continuous and Rao-Scott Chi-Square test for categorical variables. Comparison across quartiles were done with simple linear regression for continuous, Rao-Scott Chi-Square test for categorical variables. Demographics and patient confounders were adjusted using multivariate logistic regression (SAS 9.4) for odds of NAFLD/Advanced Fibrosis with respect to Mercury quartile. RESULTS: 5,590 patients were included, 44% with NAFLD and 56% without NAFLD. Patients with NAFLD vs no NAFLD were more likely to be older (51.1 vs 47.7 years, P < 0.0001), men (55% vs 45%, P < 0.0001), have fewer years of schooling, >high school (60% vs 69%, P < 0.0001), have lower Mercury levels (1.25 vs 1.68, P < 0.0003) and were significantly more likely to have higher BMI, Diabetes incidence, Hypertension, Total Cholesterol. Demographic and clinical characteristics for increased Mercury Levels by Quartile are listed in Table 1. Of note, participants with more Mercury exposure, in quartile 4 vs quartile 1, were older (53.4 vs 45.6 years, P < 0.0001), more educated (>high school 79% vs 53%, P < 0.0001), leaner (BMI 27.4 vs 29.6, P < 0.0001), higher HDL (55.8 vs 50.1), but had similar rates of GGT, ALT, AST, Hypertension, and Diabetes. There was no significant association found for risk of NAFLD or Advanced Fibrosis with Blood Mercury levels in both univariate or multivariate analysis. CONCLUSION: Our results show that Mercury levels are decreased in NAFLD, and are with increased with higher education and lower BMI. Mercury levels did not significantly affect liver enzymes or NAFLD risk factors such as hypertension and diabetes. Further studies are needed to examine Mercury toxicity and liver function.