Low thyroid function tied to mortality in NAFLD

Low thyroid function is associated with nonalcoholic fatty liver disease (NAFLD) and predicts all-cause and cardiovascular mortality in NAFLD patients, suggests a US study.

The authors used the National Health and Nutrition Examination Survey (NHANES) III from 1988 to 1994 and NHANES III-linked mortality data through 2015 for this study, as well as Cox proportional hazard model to analyse the all-cause and cause-specific mortality.

NAFLD was characterized by ultrasonographically diagnosed hepatic steatosis without coexisting liver diseases. Subclinical hypothyroidism was defined as a thyroid-stimulating hormone (TSH) level >4.5 mIU/L and “low-normal” thyroid function as higher TSH level (2.5–4.5 mIU/L) within the euthyroid reference range.

Multivariate logistic regression analysis revealed an association between low thyroid function and NAFLD in a dose-dependent manner. In the univariate model, low thyroid function also correlated with increased all-cause mortality during a median follow-up of 23 years. It was also a predictor of higher risk for all-cause mortality in individuals with NAFLD but not in those without.

In addition, low thyroid function correlated with a higher risk for cardiovascular mortality in the entire population and among those with NAFLD. However, it did not correlate with the non-NAFLD group.

“Higher levels of TSH in the euthyroid state can negatively affect the metabolic health, including NAFLD,” the authors said.