Abstract: Objective The aim of this study was to investigate the coincidence of autoimmune thyroid diseases (AITD) in patients with autoimmune hepatitis (AIH) and primary biliary cirrhosis (PBC). Methods A total of 41 patients with AIH and 45 patients with PBC were recruited in this study between June 2018 and December 2020, and serum anti-nuclear antibody (ANA), anti-mitochondrial antibody (AMA) and/or anti-mitochondrial antibody M2 (AMA-M2), anti-smooth muscle antibody (ASMA), anti-double-stranded DNA antibody (anti-dsDNA) and anti-centromere antibody (ACA) were detected. Results Out of 41 patients with AIH in our series, 12 patients had Hashimoto's thyroiditis (HT), and 6 had Grave's disease (GD), and out of 45 patients with PBC, 8 had HT, and 7 had GD; serum IgG level in patients with AIH was 17.5(14.8,19.8)g/L, significantly lower than [21.6(17.5, 29.0)g/L, P<0.05] in patients with AIH and HT or [22.4(20.2, 26.4)g/L, P<0.05] in patients with AIH and GD, serum γ-globulin level was 22.2(19.3, 25.6)%, significantly lower than [26.5(22.2, 32.2)%, P<0.05] in patients with AIH and HT or [27.1(24.3, 32.0)%, P<0.05] in patients with AIH and GD; the age of patients with PBC was (55.2±1.1)yr old, significantly younger than [(62.4±1.6) yr old, P<0.05] in patients with PBC and HT or [(62.2±1.5)yr old, P<0.05] in patients with PBC and GD, serum IgG level was 15.4(12.2, 18.0)g/L, significantly lower than [20.3(16.8, 24.7)g/L, P<0.05] in patients with PBC and HT or [21.3(16.8, 25.6)g/L, P<0.05] in patients with PBC and GD, serum γ-globulin level was 21.2(17.8, 25.6)%, significantly lower than [26.7(21.7, 30.4)%, P<0.05] in PBC patients with HT or [25.4(22.2, 29.4)%, P<0.05] in patients with PBC and GD. Conclusion The coincidence of AITD in patients with AILD is common, and serum IgG and γ-globulin levels increase in patients with AIH or PBC with concomitant AITD, which needs further investigation.

Key words: Autoimmune hepatitis, Primary biliary cirrhosis, Autoimmune thyroid diseases, Prevalence