Relationship between Hypothyroidism and Non-Alcoholic Fatty Liver Disease: A Systematic Review and Meta-analysis

Abstract

Background: Previous studies propose that hypothyroidism might play a crucial role in the pathogenesis of non-alcoholic
fatty liver disease (NAFLD), but findings from published studies on the relationship between hypothyroidism and NAFLD
are still controversial. Our study aimed to make a comprehensive evaluation of the relationship between hypothyroidism
and NAFLD through a meta-analysis.
Methods: The pooled odds ratios (ORs) with 95% confidence intervals (95% CIs) were calculated to evaluate the strength
of the relationship between hypothyroidism and NAFLD through meta-analysis.
Results: Thirteen articles were ultimately included in our meta-analysis. Meta-analysis of the 13 studies found a high
correlation between hypothyroidism and NAFLD (OR = 1.52, 95% CI 1.24–1.87, P < 0.001). Meta-analysis of 9 studies
providing adjusted ORs found that hypothyroidism was independently correlated with NAFLD (OR = 1.72, 95% CI
1.32–2.23, P < 0.001). Subgroup analysis found that both overt hypothyroidism and subclinical hypothyroidism were
significantly correlated with NAFLD, and the pooled ORs were 1.70 (95% CI 1.23–2.36, P = 0.002) and 1.40 (95% CI
1.10–1.77, P = 0.006), respectively. Besides, meta-analysis of studies providing adjusted ORs also found that both overt
hypothyroidism and subclinical hypothyroidism were independently correlated with NAFLD, and the pooled ORs were
1.81 (95% CI 1.30–2.52, P < 0.001) and 1.63 (95% CI 1.19–2.24, P = 0.002), respectively.
Conclusion: The meta-analysis provides strong epidemiological evidence for the relationship between hypothyroidism
and NAFLD. Both individuals with subclinical and overt hypothyroidism are at higher risk for NAFLD than euthyroid
subjects.