Abstract
BackgroundThyroid dysfunction can affect fertility and miscarriage risk by affecting the process of follicular growth, embryo development, implantation, and placental formation. It has been suggested that thyroid disorders are associated with ovarian reserve by affecting the follicular process. The aim of the present study was to investigate the relationship between thyroid hormone levels and ovarian reserve.MethodsThree hundred fourteen women with infertility due to various etiologies were enrolled in this study (172 individuals with Anti-Mullerian hormone (AMH) level ≥ 1.1 ng/ml and 142 individuals with AMH < 1.1 ng/ml). Serum levels of follicle-stimulating hormone (FSH), estradiol (E2) on day 2–4 of menstrual cycles, AMH, Thyroid-stimulating hormone (TSH), and thyroxine (free T4) were evaluated.ResultsIn participants with age over 35 years, median TSH level in women with AMH < 1.1 ng/ml was significantly higher than those with AMH ≥1.1 ng/ml (P-value =0.037). There was no significant difference in body mass index (BMI) in patients with age older than 35 years and younger than 35 years sub-groups based on AMH level (P-value = 0.102, and P-value = 0.909 respectively). With one unit increase in TSH level, the odds of having AMH < 1.1 ng/ml increases by 1.25 times or by 25% (P-value =0.017). Receiver operator characteristic (ROC) curve analysis showed a TSH cut-off point of 1.465 mIU/L in participants over 35 years in identifying decreased AMH level.ConclusionOur study supports the relationship between TSH level and ovarian reserve so that with an increase in TSH from a certain level is associated with a decrease in ovarian function.
Highlights
Thyroid dysfunction can affect fertility and miscarriage risk by affecting the process of follicular growth, embryo development, implantation, and placental formation
In the process of folliculogenesis, thyroid hormones bound to thyroid-binding globulin (TBG) increases with increasing serum estrogen levels, and the result of these phenomena is a decrease in free thyroxin and an increase in Thyroid-stimulating hormone (TSH) level [6]
Exclusion criteria were any iatrogenic cause for decreased ovarian reserve such as ovarian surgery, radiotherapy and chemotherapy, endometriosis, history of known thyroid disorders, levothyroxine users, polycystic ovarian syndrome (PCOS), and patients who declined to participate in the study
Summary
Thyroid dysfunction can affect fertility and miscarriage risk by affecting the process of follicular growth, embryo development, implantation, and placental formation. It has been suggested that thyroid disorders are associated with ovarian reserve by affecting the follicular process. Decreased ovarian reserve and subsequent reduction in the quantity and quality of oocytes is a process that depends on age. This phenomenon can occur at any age. In younger patients, it is mostly idiopathic but there are other causes such as ovarian surgery, One of the factors affecting the functional reserve of the ovary is thyroid disorders. TSH has a synergistic effect with follicle stimulating hormone (FSH) in promoting the proliferation of granulosa cells [4]. It plays an important role in the process of follicle development [5] and its dysregulation may impair follicular development
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