Association between Thyroid Function and Ovarian Reserve in Infertile Women: A Cross-sectional Study

Abstract

Introduction: Thyroid dysfunctions are among the most common diseases in women of reproductive age group. Thyroid hormone receptors are present on oocytes which indicate that thyroid hormones may influence ovarian functions. Serum AntiMüllerian Hormone (AMH) is secreted from growing granulosa cells of ovaries. Serum AMH concentrations are used to evaluate ovarian reserve in females. Aim: To find the association between ovarian reserve, measured by AMH concentration and thyroid functions in women with infertility. Materials and Methods: This cross-sectional study was conducted in Department of Biochemistry at Government Medical College, Badaun, Uttar Pradesh, India, from July 2021 to December 2021. The involved women with infertility in the age group of 20 to 40 years attending the infertility clinic. Participants were divided into two groups based on whether the serum AMH value was <1 ng/mL (lower than low normal ovarian reserve) or ≥1 ng/mL (low normal to normal ovarian reserve). The blood samples were processed for Serum Thyroid Stimulating Hormone (TSH), free Triiodothyronine (fT3 ), free Thyroxine (fT4), Prolactin and AMH. The median values of TSH and fT4 levels were compared in the subgroups of patients defined by the level of serum AMH i.e., serum AMH value <1 ng/mL, and serum AMH value ≥1 ng/mL. Chi-square test was used to establish the association between the categorical variables. Results: Based on serum AMH values, 22 (28%) females had below normal ovarian reserve i.e., serum AMH value <1 ng/mL, and 56 (72%) females had low normal to normal ovarian reserve i.e., serum AMH value ≥1 ng/mL. The mean age of participants with AMH <1 ng/mL was 33.23±4.28, which was significantly higher than those with AMH value ≥1 ng/mL (p-value=0.002). Serum TSH value was significantly higher in the subgroup of participants with AMH <1 ng/mL, the value being 4.75 mIU/L and was lower (2.8 mIU/L) in the subgroup of participants with AMH ≥1 ng/mL (p-value=0.002). Conclusion: In conclusion, the present study found the highly significant difference in serum TSH values in the two groups based on whether the serum AMH value was <1 ng/mL and ≥1 ng/mL suggesting that subclinical hypothyroidism has negative impact on the female fertility. Increasing age of the females was negatively correlated with the ovarian reserve.