The relationship between thyroid hormones and insulin resistance in polycystic ovary syndrome women

<b><i>Objective:</i></b> This study aimed to investigate the changes in thyroid hormones in the serum of patients with polycystic ovary syndrome (PCOS) and their correlation with insulin resistance. <b><i>Design:</i></b> This is a retrospective study. <b><i>Participants:</i></b> 84 patients having insulin resistance and 76 patients without insulin resistance were included. 90 women without history of PCOS were selected as a healthy control group. <b><i>Settings:</i></b> This study was conducted at Shijiazhuang Fourth Hospital. <b><i>Methods:</i></b> Blood samples were collected from each group on days 3–5 of their menstrual cycle, and their triiodothyronine (T3), thyroxine (T4), and thyroid-stimulating hormone (TSH) levels were analyzed and compared between groups. <b><i>Results:</i></b> We investigated the changes of serum thyroid hormones in patients with PCOS and their correlation with insulin resistance. We found that serum levels of T3 and T4 were significantly decreased, while TSH levels were significantly increased in PCOS patients compared with HCs. Moreover, we found that patients with insulin resistance had significantly lower levels of serum T3 and T4 and higher levels of TSH compared to those PCOS participants without insulin resistance. <b><i>Limitations:</i></b> This study was a retrospective and single-center study, which had selection bias, information bias, and confounding variables may affect the accuracy and reliability of the conclusion. <b><i>Conclusions:</i></b> Insulin resistance negative correlates with their serum T3, T4, and positive correlates with their TSH levels. Our results develop a combined test model with the serum T3, T4, and TSH levels for the clinical diagnosis of insulin resistance in PCOS women.