Is hypothyroidism a risk factor for non-alcoholic steatohepatitis?

Thyroid hormones play an important role in the regulation of lipid and carbohydrate metabolism, both of which are affected in patients with non-alcoholic steatohepatitis (NASH). Anecdotally, we have observed that a number of patients with NASH carried a diagnosis of hypothyroidism. However, it is unknown if thyroid dysfunction plays any role in the pathogenesis of NASH. To further investigate this observation, we conducted a case-control study to determine the association between hypothyroidism and NASH.

Cases were defined as patients with well-documented NASH attending hepatology clinics at Indiana University Hospital from January 1, 1995 to December 31, 2000. Age, gender, race, and body-weight matched individuals seen during the same period in the general medical clinics served as controls. Patients with a previous diagnosis of hypothyroidism who are currently on synthetic T4 replacement were considered to be "hypothyroid". The strength of association was assessed by logistic regression analysis after controlling for the frequency of diabetes mellitus, hyperlipidemia, and hypertension.

One hundred seventy-four patients with NASH (cases) and 442 controls were included. The mean age of cohort was 49 +/- 13 years, 59% were female, and 98% were white. The prevalence of hypothyroidism in patients with NASH was 15% was significantly higher than in the controls (7.2%, P < 0.001). By multivariate analysis, the prevalence of hypothyroidism in the NASH group was significantly higher than in control group (OR: 2.3, 95% CI: 1.2-4.2, P = 0.008).

These data suggest that hypothyroidism is associated with human NASH. Further research is needed to confirm this finding and to understand its implications.