Subclinical and clinical hypothyroidism and non-alcoholic fatty liver disease: a cross-sectional study of a random population sample aged 18 to 65 years

Abstract

Background: Non-alcoholic fatty liver disease (NAFLD) is one of the most common disorders of the liver worldwide. Recently, a correlation between thyroid dysfunction and NAFLD has been discussed. Objective of the present study was to investigate the association between thyroid dysfunction and hepatic steatosis.

Methods: Data from 2,445 subjects (51.7% females) aged 18 to 65 years participating in a population-based cross-sectional study were assessed based on a standardized questionnaire and documentation of physical, biochemical and ultrasonographic findings. After application of exclusion criteria, a total of 1,276 subjects were included in the study collective. The influence of potential factors on the development of hepatic steatosis was assessed using multivariate logistic regression.

Results: The prevalence of hepatic steatosis in the study collective was 27.4% (n = 349). The serum thyroxin (TT4) concentration in subjects with hepatic steatosis was reduced (p =0.0004). Adjusting for age, or BMI, there was an increased prevalence of hepatic steatosis in subjects with reduced TT4 concentrations (p = 0.0143; p = < .0001).

Conclusions: The findings of the present study confirm an association between both subclinical and clinical hypothyroidism and hepatic steatosis.

Fig. 1

Flow of the subjects across the study. The base collective for the present study consisted of the 2,445 subjects of the EMIL study. Of these, 258 subjects were excluded due to age < 18 years; 69 due to excessive alcohol consumption (>40 g/day in males and > 20 g/day in females); 146 due to past or current hepatitis B or hepatitis C infections;intake of iodone (n = 344), antithyroid agents (n = 2) or thyroid hormones (n = 437); and 1 due to hemochromatosis. Incomplete data, laboratory values or other data were also exclusion criteria. Each box represents an exclusion criterion and contains the corresponding number of subjects in relation to the total collective. An individual subject may meet multiple exclusion criteria. For the present study, the resulting collective consisted of 1,276 individuals

Fig. 2

Prevalence of non-alcoholic fatty liver disease (NAFLD) in relation to thyroid function in the present study. The figure plots the thyroid hormone concentrations in their respective quartiles (x-axis) against NAFLD prevalence rates in percent (y-axis). NAFLD prevalence rates show a downward trend with increasing TT4 concentrations. In addition, a positive trend is also seen for NAFLD prevalence rates with increasing TSH levels in the first quartile