Thyroid Peroxidase Antibodies in Infertile Women with Polycystic Ovary Syndrome.

To compare the rate of positive thyroid peroxidase antibodies (TPO Ab) between women with different polycystic ovary syndrome (PCOS) phenotypes and women without PCOS. This is a retrospective cohort study. Women with PCOS at My Duc Hospital between June 1, 2020, and March 27, 2021, were matched with non-PCOS women by age. TPO Ab (cut-off: 34 IU/mL) and thyroid-stimulating hormone (TSH) levels were measured as markers of Hashimoto thyroiditis and thyroid function, respectively. One thousand eight hundred eight infertile women were included, 904 with PCOS (mean age 29.0 ± 3.58 years) and 904 without PCOS (29.1 ± 3.4 years; controls). Women with PCOS had a higher body mass index (22.8 ± 3.84 vs. 19.9 ± 2.23 kg/m2, p < 0.001), but most were not overweight/obese. Rates of positive TPO Ab in women with versus without PCOS were 8.2% and 8.4%, respectively (p = 0.932). Rates of positive TPO Ab in patients with PCOS phenotype A, B, C, or D were not statistically different (7.5%, 2.9%, 20.0%, and 7.8%, respectively). Median TSH concentrations were similar in the PCOS and control groups (1.84 mIU/L vs. 1.78 mIU/L, respectively; p = 0.194). Based on a linear regression model, there was no correlation between either BMI or the estradiol to progesterone ratio and TPO Ab status. In a large population of infertile women with PCOS who were mostly lean patients, rates of positive TPO Ab across all four PCOS phenotypes did not differ significantly from those in women without PCOS. These findings did not support the hypothesis that PCOS is a risk factor for Hashimoto thyroiditis.