Relationship between autoimmune liver disease and autoimmune thyroid disease: a cross-sectional study.

Background: A high prevalence of autoimmune thyroid disease (AITD) has been observed in patients with autoimmune liver disease (AILD); however, data on the clinical relationship between AILD and AITD remain scant. We aimed to evaluate the relationship between AILD and AITD.Methods: We performed a retrospective study using medical records from 324 patients with AILD, 113 of whom had concurrent AITD.Results: Patients with autoimmune hepatitis (AIH) were more likely to develop AITD (45.8%), followed by autoimmune hepatitis-primary biliary cholangitis overlap syndrome (AIH-PBC OS) (39.5%) and PBC (22.6%). Patients with concurrent AILD and AITD showed higher levels of immunoglobulin G (IgG) (21.5 g/L vs 16.3 g/L, p < .0001) and gamma globulin (γ-globulin) (27.1% vs 21.9%, p < .0001). IgG was positively correlated with thyroid antibodies [thymoglobulin antibody (TGAb) and thyroperoxidase antibody (TPOAb)] (r = 0.396, 0.322; p < .0001, p = .002, respectively). TPOAb positivity was highest in PBC patients with concurrent AITD (83.9%). Patients with concurrent PBC and AITD were significantly older than those with PBC alone (p = .0004). Patients with concurrent AIH and AITD had a higher homogenous nuclear pattern of antinuclear antibody positivity compared to those with AIH alone (p = .019). Thyroid dysfunction in AILD patients with concurrent AITD was principally characterized by Hashimoto's thyroiditis (65.5%), and diffuse lesions were mainly found by thyroid ultrasound (53.1%).Conclusions: The high incidence of AILD concomitant with AITD, the higher levels of serum IgG and γ-globulin, and the strong correlation between thyroid antibodies and IgG suggest that close screening for AITD and accurate physical examinations should be performed for all patients with AILD.