Nonalcoholic fatty liver disease in a cluster of Iranian population: thyroid status and metabolic risk factors

This study aimed to investigate the prevalence, metabolic risk factors, and thyroid dysfunction among a healthy urban population.

In a cross-sectional study, the patients were evaluated for nonalcoholic fatty liver disease (NAFLD) using ultrasonography. The participants' characteristics such as age, sex, weight, height, body mass index (BMI), waist circumference, hip circumference, waist-to-hip ratio, systolic and diastolic blood pressure, and history of diabetes, ischemic heart disease (IHD), hypertension, and hyperlipidemia were recorded using a data gathering form. The patients were compared to those without NAFLD in terms of metabolic factors and thyroid abnormalities.

From 832 participants, 127 (15.3%) individuals had NAFLD.  Metabolic syndrome was detected in 39 participants (30.70 %) with NAFLD and in 85 participants (12.05%) without NAFLD (P < 0.001) (OR: 3.22; 95 % CI: 2.07-5.01). In multivariate logistic regression analysis BMI, waist-to-hip ratio, and higher serum ALT levels were independent predictors for NAFLD (P < 0.001). There was no statistically significant difference in serum TSH, free T4, and free T3 levels between the participants with NAFLD and the participants without NAFLD (P > 0.05). Neither hypothyroidism nor markers of thyroid autoimmunity were associated with NAFLD in our study population (P > 0.05). Serum TSH was categorized according to 25th, 50th, and 75th percentile to <1.29 mIU/L, 1.29-1.91 mIU/L, 1.91-2.77 mIU/L, and >2.77 mIU/L. Compared with non-NAFLD participants, the diagnosis of NAFLD was significantly higher in the low TSH group (P = 0.004).

Central obesity as reflected by waist-to-hip ratio is one of the major risk factors for NAFLD. However, thyroid dysfunction was not correlated with NAFLD and the observed alterations in thyroid hormones are due to sick euthyroid syndrome.