Thyroid dysfunction is prevalent in autoimmune hepatitis: A case control study

Background: Autoimmune hepatitis (AIH) may be associated with other autoimmune diseases. Autoantibodies are common in AIH suggesting their potential role in the pathogenesis of the disease. Among these autoantibodies, thyroid autoantibodies have been reported in patients with chronic hepatitis, with greater prevalence in patients with chronic hepatitis C infection. Objectives: To assess the prevalence of thyroid dysfunction among patients with AIH. Methods: In this case-control, retrospective study, we examined patients diagnosed with AIH according to both the original and revised international AIH group scoring systems. Patients with other hepatic pathologies were excluded AIH was evaluated as an independent risk factor for thyroid disease by a logistic regression model. Univariate and multivariate regression analyses were conducted using hypothyroidism and hyperthyroidism as the dependent variables. Results: Our cohort comprised 163 patients diagnosed with AIH and 1104 healthy age- and gender-matched controls. Hypothyroidism was more prevalent among those with AIH compared to controls (17.7% vs. 5%, respectively, 95% confidence interval [95%CI] 1.68-2.48, P < 0.001). Hyperthyroidism was more prevalent in AIH patients compared to controls (odds ratio 3.2% and 1.2%, respectively, 95%CI 1.68-2.47, P < 0.001). Using a multivariate logistic analysis, we found an independent association between AIH and hypothyroidism but not with hyperthyroidism. Conclusions: Thyroid dysfunction is more prevalent in patients with AIH. Whether thyroid dysfunction is the cause or a risk factor for AIH, or vice versa, is still unclear. Screening for thyroid dysfunction is warranted after AIH is diagnosed.