Associations of Serum Uric Acid Level With Liver Enzymes, Nonalcoholic Fatty Liver Disease, and Liver Fibrosis in Korean Men and Women: A Cross-Sectional Study Using Nationally Representative Data

BACKGROUND: This study aimed to determine whether serum uric acid (SUA) levels are associated with various indices of liver damage in the adult Korean population. METHODS: We used the Seventh (VII) Korean National Health and Nutritional Examination Surveys. Our study population comprised 6,007 men and 8,488 women. Levels of SUA were divided into four groups (≤ 5.3, 5.3–6.0, 6.0–7.0, and > 7.0 mg/dL for men and ≤ 4.0, 4.0–4.8, 4.8–6.0, and > 6.0 mg/dL for women). Elevated liver enzyme levels were defined as > 35 (men) and > 31 (women) IU/L for aspartate aminotransferase (AST), > 45 (men) and > 34 (women) IU/L for alanine aminotransferase (ALT). Hepatic steatosis index and fibrosis (FIB)-4 index was used to determine nonalcoholic fatty liver disease (NAFLD) and liver FIB, respectively. Adjusted odds ratios (aORs) were calculated by logistic regression analysis for liver enzymes, NAFLD, and liver FIB, according to the SUA level. RESULTS: Among women, the 4.8–6.0 and > 6.0 mg/dL SUA groups showed higher ORs of elevated AST (aOR, 1.78 and 2.03; 95% confidence interval [CI], 1.37–2.32 and 1.40–2.96, respectively; P < 0.001) and the 4.0–4.8, 4.8–6.0, and > 6.0 mg/dL SUA groups showed a higher ORs of ALT elevation (aOR, 1.35, 2.26, and 2.37; 95% CI, 1.02–1.79, 1.72–2.97, and 1.60–3.50, respectively; P < 0.001) compared to the lowest level SUA group. Among women with normal ALT, > 6.0 mg/dL SUA group showed higher OR of NAFLD status (aOR, 1.52; 95% CI, 1.06–2.19). Among men and women with NAFLD, hyperuricemia showed higher ORs of liver FIB (aOR, 2.25 and 1.89; 95% CI, 1.21–4.19 and 1.09–3.27, respectively) than the lowest level SUA group. CONCLUSION: High SUA levels may be associated with elevated liver enzymes and NAFLD, mainly in women. Even in women with normal ALT levels, SUA levels may predict the NAFLD status. Hyperuricemia may predict advanced liver FIB in both men and women with NAFLD. Further studies investigating the causal effects of SUA on liver damage are required.