MPO and autoimmune thyroid disease: There were no significant differences in the prevalence of ANA, SSA, SSB, anti-dsDNA, anti-RNP, ANCA/MPO or ANCA/PR3 between PCOS and controls. The prevalence of ACLA IgG was higher in controls than PCOS (5.4% v.s. 0%, P=0.011). Patients had a higher prevalence of anti-TPO antibodies (18.75% v.s. 7.35%, P=0.045) and slightly but not significantly higher prevalence of autoimmune thyroiditis (18.75% v.s. 10.29%) than controls.