Evaluation of ovarian reserve in women with overt or subclinical hypothyroidism

Thyroid dysfunction and female infertility. A comprehensive review

INTRODUCTION

Female infertility is defined as the inability to achieve pregnancy following one year of consistent, unprotected sexual intercourse. Among the various endocrine factors contributing to this complex issue, thyroid dysfunction assumes a pivotal and noteworthy role.

METHODS

A narrative review, encompassing 134 articles up to 2023, was conducted utilizing the PubMed/Medline, EMBASE, and Scielo databases. The primary focus of this review was to investigate the effects of thyroid dysfunction on female infertility.

RESULTS

Thyroid disorders exert a significant influence on folliculogenesis, fertilization, and implantation processes. Thyroid autoimmunity, although associated with diminished ovarian reserve, does not typically necessitate levothyroxine therapy. On the other hand, both subclinical and overt hypothyroidism often require levothyroxine treatment to enhance fertility and optimize obstetric outcomes. Hyperthyroidism warrants prompt intervention due to its heightened risk of miscarriage. Furthermore, thyroid dysfunction exerts notable effects on assisted reproductive technologies, underscoring the importance of achieving euthyroidism prior to ovarian stimulation.

CONCLUSION

Women presenting with thyroid dysfunction must undergo meticulous and individualized assessments since fertility outcomes, whether achieved through natural conception or assisted reproductive technologies, can be significantly influenced by thyroid-related factors.

Evaluation of the ovarian reserve in women and adolescent girls with Hashimoto's thyroiditis by serum anti-Müllerian hormone level: A systematic review and meta-analysis

Objectives

Several researchers performed case-control studies to explore the relationship between Hashimoto's thyroiditis(HT) and ovarian reserve using anti-Müllerian hormone(AMH) in adolescent girls and women. But the results among these studies are inconsistent and the relationship between HT and ovarian reserve is still controversial. The study aimed to conduct the meta analysis of case-control studies to confirm the relationship between HT and ovarian reserve using AMH.

Methods

6 electronic databases including PubMed, EMBASE, the Cochrane Library, China National Knowledge Internet(CNKI), SinoMed and Wanfang were searched from inception to December 2021. Endnote X7.0 software was applied to managing all the relevant records. Then data extraction and evaluation of methodological quality of included studies were conducted after two-step selection.Review manager 5.4 version software and Stata 12.0 version software were used to perform all statistical analyses.

Results

10 case-control studies involving 1202 individuals were included in the present study. The preliminary results revealed AMH values were significantly higher in adolescent girls with euthyroid HT compared with healthy adolescent girls(MD = 1.97; 95%CI, 1.43-2.51; P < 0.001; I2 = 0%). The pooled results in the subgroup of female adults with euthyroid HT showed AMH values were not significantly different between patients with HT and healthy women(MD = -0.21; 95%CI, -0.51-0.09; P = 0.18; I2 = 38%). The pooled results in the two subgroups of female adults with subclinical hypothyroidism and overt hypothyroidism both showed AMH values were significantly lower in the HT group compared with healthy women [(MD = -0.60; 95%CI, -0.86 to -0.34; P < 0.001; I2 = 0%), (MD = -1.34; 95%CI, -1.94 to -0.74; P < 0.001; I2 = 65%)].

Conclusions

Ovarian reserve evaluated by serum AMH concentration is affected by female adults with subclinical hypothyroidism and overt hypothyroidism. The AMH level was significantly higher in euthyroid adolescent girls.

Polycystic ovary syndrome and thyroid disorder: a comprehensive narrative review of the literature

Background

Published data on the relationship between polycystic ovary syndrome (PCOS) and thyroid dysfunction are sparse and confusing.

Objective

To comprehensively review data available in the literature regarding the relationship between PCOS and the thyroid function, and its abnormalities.

Methods

Nine main areas of interest were identified and analyzed according to the available evidence: 1) Evaluation of thyroid function for PCOS diagnosis; 2) Epidemiology data on thyroid function/disorders in patients with PCOS, and vice versa; 3) Experimental data supporting the relationship between thyroid function/disorders and PCOS; 4) Effects of thyroid function/disorders on PCOS features, and vice versa; 5) Effect of thyroid alterations on the cardiometabolic risk in women with PCOS; 6) Effect of thyroid abnormalities on reproductive outcomes in women with PCOS; 7) Relationship between thyroid function/abnormalities in patients with PCOS who are undergoing fertility treatment; 8) Effect of treatments for thyroid diseases on PCOS; and 9) Effect of treatments for PCOS on thyroid function. An extensive literature search for specific keywords was performed for articles published from 1970 to March 2023 using PubMed and Web of Science. Data were reported in a narrative fashion.

Results

PCOS is a diagnosis of exclusion for which diagnosis is possible only after excluding disorders that mimic the PCOS phenotype, including thyroid dysfunctions. However, the tests and the cutoff values used for this are not specified. Many experimental and clinical data suggest a relationship between perturbations of the thyroid function and PCOS. Direct and unequivocal evidence on the effects of thyroid function/disorders on PCOS features are lacking. High thyroid-stimulating hormone levels and subclinical hypothyroidism may be associated with significant worsening of several intermediate endpoints of cardiometabolic risk in women with PCOS. Thyroid abnormalities may worsen reproductive outcomes, especially in patients undergoing fertility treatment. To date, there are no data demonstrating the efficacy of thyroid medications on fertility and cardiometabolic risk in women with PCOS. Lifestyle modification changes, metformin, and vitamin D seem to improve thyroid function in the general population.

Conclusion

PCOS and thyroid disorders are closely related, and their coexistence may identify patients with a higher reproductive and metabolic risk. Regular screening for thyroid function and thyroid-specific autoantibodies in women with PCOS, particularly before and during pregnancy, is highly recommended.

Factors Associated with Poor Ovarian Reserve in Young Infertile Women: A Hospital-based Cohort Study

Background

In practice, we encounter many young infertile women with poor ovarian reserve though ovarian reserve starts to decline after 35 years of age. One of the established risk factors for poor ovarian reserve in young women is endometriosis. There are other conditions that are reported to be associated which require further research.

Aims

We aimed to study the prevalence of poor ovarian reserve and to find out the associated factors in women who are <35 years of age.

Settings and Design

This was a prospective observational cohort study conducted in a tertiary care setting.

Materials and Methods

Women aged more than 21 years and <35 years without Polycystic Ovarian Syndrome (PCOS) or ovarian dysgenesis with normal male factor were included after ethical approval. The sample size was 166 and serum anti-Mullerian hormone (AMH) was estimated by immunoenzymatic assay and expressed in ng/ml. AMH ≤0.99 ng/ml was considered poor ovarian reserve. Apart from established risk factors, the proposed risk factors studied were age 31-35 years, presence of medical disorders, gynaecological pathology and history of repeated ovulation induction (OI).

Statistical Analysis Used

Data were analysed by SPSS version 25. Chi-square test and Fisher's exact test were used to compare the variables between normal ovarian reserve and poor ovarian reserve. Risk estimation was done by logistic regression and was expressed in odds ratio (OR).

Results

Poor ovarian reserve was diagnosed in 40% of this cohort, and 62% were between 31 and 35 years. After adjusting for age >30 years, women with endometrioma, hypothyroidism and prior history of ≥3 cycles of OI were found to be having poor ovarian reserve (OR was 5.7, 2.5 and 2.3, respectively).

Conclusion

Poor ovarian reserve was present in 40% of young women, and significantly associated factors were hypothyroidism and history of repeated multiple OI. This could be a confounder for other underlying mechanisms driving early exhaustion of ovarian reserve in certain young women. Hence, along with established risk factors, these women should undergo AMH testing irrespective of age.

A review of autoimmunity and immune profiles in patients with primary ovarian insufficiency

Primary ovarian insufficiency (POI) is a complicated clinical syndrome characterized by progressive deterioration of ovarian function. Autoimmunity is one of the main pathogenic factors affecting approximately 10% to 55% of POI cases. This review mainly focuses on the role of autoimmunity in the pathophysiology of POI and the potential therapies for autoimmunity-related POI. This review concluded that various markers of ovarian reserve, principally anti-Müllerian hormone, could be negatively affected by autoimmune diseases. The presence of lymphocytic oophoritis, anti-ovarian autoantibodies, and concurrent autoimmune diseases, are the main characteristics of autoimmune POI. T lymphocytes play the most important role in the immune pathogenesis of POI, followed by disorders of other immune cells and the imbalance between pro-inflammatory and anti-inflammatory cytokines. A comprehensive understanding of immune characteristics of patients with autoimmune POI and the underlying mechanisms is essential for novel approaches of treatment and intervention for autoimmune POI.

Evaluation of anti-Müllerian hormone in pre-menopausal women stratified according to thyroid function, autoimmunity and age

Background

AMH is a reliable index of ovarian reserve. It is not clear whether, or how much, thyroid function and/or thyroid autoimmunity can impair ovarian function and AMH secretion in the long term.

Aim

This retrospective cross-sectional study compared AMH levels in pre-menopausal women with/without positive thyroid autoimmunity or hypofunction.

Methods

From January 2019 to May 2022, AMH was evaluated in 250 pre-menopausal women not undergoing assisted fertility procedures who were referred to a secondary endocrine centre. Thyroid function and autoimmunity, sonographically measured thyroid volume, FSH and E2 in the early follicular phase, and PRL and progesterone in the luteal phase were also evaluated. Exclusion criteria were: age < 18 years, genetic hypogonadism, pregnancy and previous treatments that have potentially damaging effects on gonads.

Results

We evaluated 171 women (mean age ± SD: 31.5 ± 9.0 years) off L-T4 treatment and 79 women on L-T4 treatment (39.7 ± 9.5 years; P < 0.001). AMH (median, IQR, CI) was 16.1 pmol/l (7.1 – 35.7 pmol/l, 21.4 – 29.9 pmol/l) and 7.6 pmol/l (1.4 – 17.8 pmol/l, 8.6 – 14.7 pmol/l; P < 0.001), respectively. When the women were stratified according to age (18-25, 26-30, 31-35, 36-40, 41-45, > 46 years) no significant difference emerged between those on/off L-T4 treatment in groups of the same age-range. In women on- or off-L-T4 treatment, AMH was negatively related with age on univariate and multivariate analyses (P < 0.0001). In both groups, AMH was negatively related to FSH (P < 0.0001). On multivariate analysis, AMH was positively related to the age of the mother on spontaneous menopause (P = 0.006) and negatively to thyroid volume (P = 0.02) in women on L-T4. AMH levels were significantly (P = 0.03) higher in TPOAb-negative than in TPOAb-positive women, but age was significantly (P = 0.001) lower in TPOAb-negative than in TPOAb-positive women.

Conclusions

In our cohort of women, age proved to be a better predictor of AMH levels than any of the other factors linked to thyroid function and autoimmunity. Our data do not support the hypothesis that subclinical hypothyroidism and/or autoimmunity are associated with decreased ovarian reserve. However, a larger number of cases is needed in order to obtain conclusive data.

Effect of hypothyroidism and thyroid autoimmunity on the ovarian reserve: A systematic review and meta-analysis

Background

Evidence suggests that hypothyroidism and thyroid autoimmunity (TAI) are possibly associated with ovarian dysfunction. This meta‐analysis aimed to investigate whether hypothyroidism and/or TAI affect the ovarian reserve and evaluated using the anti‐Mullerian hormone (AMH).

Methods

PubMed, EMBASE, Web of Science, and Cochrane Controlled Trials Register databases from inception to October 2020 were searched to identify relevant studies. Studies comparing the AMH levels between the control and the affected groups were included in the data synthesis. The primary endpoint in the meta‐analysis was AMH levels compared with the controls.

Main findings

Nine trials were included in the analysis. The AMH levels were significantly lower in the adults with euthyroid TAI (mean difference −0.12, [95% CI: −0.18 to −0.06]). The AMH levels tended to be lower in subclinical hypothyroidism and overt hypothyroidism than in the control group, although the differences were not significant. The AMH levels were significantly higher in the euthyroid TAI group in the adolescents (mean difference 2.51, [95% CI 1.82 to 3.21]).

Conclusion

TAI and hypothyroidism may affect the ovarian reserve. The opposite effects on AMH levels depending on age suggest that TAI may be implicated in the depletion of follicles in adults following extensive activation of primordial follicles in adolescence.

The relationship between thyroid function and ovarian reserve: a prospective cross-sectional study

Background

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. The aim of the present study was to investigate the relationship between thyroid hormone levels and ovarian reserve.

Methods

Three 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.

Results

In 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.

Conclusion

Our 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.

Body Composition and Serum Anti-Müllerian Hormone Levels in Euthyroid Caucasian Women With Hashimoto Thyroiditis

Objective

Women with Hashimoto thyroiditis (HT) are characterized by increased incidence of infertility and disturbances in body composition. Serum anti-Müllerian hormone (AMH), which reflects functional ovarian reserve, is decreased in women with HT and it be related to body mass. The aim of the present study was to investigate the relation between serum levels of AMH and body composition in HT compared to control group.

Patients and Methods

We examined 85 euthyroid women: 39 subjects with HT and 46 control women. Body composition was analysed by dual-energy X-ray absorptiometry and with bioimpedance method. Serum concentrations of AMH, leptin, TSH, thyroid hormones were assessed.

Results

We observed lower serum concentration of AMH in women with HT in comparison to the control group (p=0.01), but without differences in serum concentration of leptin between studied groups (p=0.28). Women with HT were characterized by higher %body fat (p=0.01) estimated with bioimpedance method without differences in BMI, android and gynoid fat mass and visceral adipose tissue (VAT) mass estimated with DXA method when compared to the control group (all p>0.05). We found a negative relationship between serum concentration of AMH and %body fat (r=-0.38,p=0.03) in women with HT. Additionally, in HT group, the relationship between serum levels of AMH and leptin was not statistically significant (r=0.01,p=0.96). We observed a relationship between serum concentration of leptin and BMI, %body fat mass, android, gynoid and VAT mass in HT and in the control group (all p<0.01).

Conclusions

Women with HT are characterized by lower levels of AMH and it is associated with higher fat mass, independently of serum levels of leptin.

Correlation Analysis Between Ovarian Reserve and Thyroid Hormone Levels in Infertile Women of Reproductive Age

OBJECTIVE

To analyze the correlation between ovarian reserve and thyroid function in women with infertility.

METHODS

Retrospective analysis of the data of 496 infertility patients who visited the clinic between January 2019 and December 2020. According to the TSH level, it is grouped into <2.5 mIU/L, 2.5~4.0mIU/L and ≥4.0 mIU/L or according to the positive/negative thyroid autoimmune antibody. The relationship was assessed through the ovarian reserve, thyroid function, and anti-Müllerian hormone (AMH) levels in infertile patients. On the other hand, the patients are divided into groups according to age (≤29 years old, 30-34 years old and ≥35 years old), basic FSH (<10 IU/L and ≥10 IU/L), and AMH levels. The ovarian reserve was evaluated through the AMH and the antral follicle count (AFC).

RESULTS

The average age of the patients was 30.31 ± 4.50 years old, and the average AMH level was 5.13 ± 4.30 ng/mL. 3.63% (18/496) of patients had abnormal TSH levels (normal: 0.35-5.5 mIU/L), the positive rate of thyroid peroxidase antibody (TPOAb) was 14.52% (72/496), the positive rate of anti-thyroglobulin antibody (TgAb) was 16.94% (84/496), and the positive rate of TPOAb and TgAb was 10.48% (52/496). After grouping according to TSH level or thyroid autoimmune antibody positive/negative grouping, the analysis found that there was no statistical significance in age, AMH level and basic FSH level among the groups (P>0.05). There were no significant differences in the levels of TSH, FT3, and FT4 among different ages, AMH, and FSH levels (P>0.05).

CONCLUSION

There is no significant correlation between ovarian reserve and thyroid function in infertile women.

Overtime trend of thyroid hormones and thyroid autoimmunity and ovarian reserve: a longitudinal population study with a 12-year follow up

BACKGROUND

Ovarian reserve, vital for reproductive function, can be adversely affected by thyroid diseases. Despite alternations of thyroid hormones with ageing, data on interactions between the overtime trend of thyroid functions and ovarian reserve status has rarely been reported. We aimed to examine the overtime trend of thyroid hormones, thyroid peroxidase antibody (TPO Ab) and their associations with ovarian reserve status, identified by levels of age specific anti-mullerian hormone (AMH) in reproductive aged women, who participated in 12-year cohort of Tehran Thyroid Study (TTS).

METHODS

Reproductive age women(n = 775) without any thyroid disease or ovarian dysfunction were selected from the Tehran Thyroid Study cohort. Participants were divided into four age specific AMH quartiles (Q1-Q4), Q1, the lowest and Q4, the highest. AMH was measured at the initiation of study and thyroid stimulating hormone (TSH), free T4 (FT4), and TPO Ab were measured at baseline and at three follow up visits.

RESULTS

At baseline, there was no statistically significant difference in thyroid hormones between women of the four quartiles, although TPO Ab levels were higher in women of Q1. During the follow ups, FT4 was decreased in all quartiles (p < 0.05), whereas TPO Ab increased in Q1 (p = 0.02). Odds ratio of overall TPO Ab positivity in women of Q1 was 2.08 fold higher than those in Q4. (OR: 2.08, 95%CI: 1.16, 3.72; p = 0.01).

CONCLUSION

Women with the lowest ovarian reserves had higher levels of TPO Ab, with a positive trend of this antibody overtime in comparison to other quartiles, indicating that this group may be at a higher risk of hypothyroidism over time.