Correlation between thyroid hormone sensitivity and the risk of polycystic ovary syndrome

OBJECTIVE

There has been some confusion in earlier research on the connection between thyroid function and polycystic ovary syndrome (PCOS). This research is aimed to probe into the correlation between thyroid condition and the risk of PCOS from a new standpoint of thyroid hormone sensitivity.

METHODS

This research comprised 415 females with PCOS from Drum Tower Hospital Affiliated with the Medical School of Nanjing University, and 137 non-PCOS individuals were selected as the normal control. Based on free thyroxine (FT4), free triiodothyronine (FT3), and thyroid-stimulating hormone (TSH), we calculated the thyroid hormone sensitivity indices, which consist of Thyroid Feedback Quantile-based Index (TFQI), Thyroid-stimulating Hormone Index (TSHI), Thyrotroph Thyroxine Resistance Index (TT4RI) and Free Triiodothyronine /Free thyroxine (FT3/FT4). The binary logistic regression model was adopted to investigate the correlation between thyroid hormone sensitivity indices with the risk of PCOS. Pearson or Spearman correlation analysis was employed to explore the association among thyroid-related measures with metabolic parameters in PCOS.

RESULTS

Results of this research showed that females with PCOS had rising TFQI, TSHI, TT4RI, and FT3/FT4 levels compared with the control group. After adjustment for the impact of various covariates, there was no significant correlation between FT3/FT4 and the risk of PCOS; However, the odds ratio of the third and fourth vs. the first quartile of TFQI were 3.57(95% confidence interval [CI]:1.08,11.87) and 4.90(95% CI:1.38,17.38) respectively; The odds ratio of the fourth vs. the first quartile of TSHI was 5.35(95% CI:1.48,19.37); The odds ratio of the second vs. the first quartile of TT4RI was 0.27(95%CI 0.09,0.82). In addition, no significant correlation was observed between thyroid-related measures and metabolic measures in females with PCOS.

CONCLUSIONS

A reduction in the sensitivity of central thyroid hormone is closely correlated with a higher risk of PCOS. Further research is necessary to corroborate our findings and the supporting mechanisms.

Positive Thyroid Peroxidase Antibody among Women with Polycystic Ovarian Syndrome Visiting an Infertility Clinic at a Tertiary Care Centre

Introduction

Polycystic ovarian syndrome is the most common endocrine-metabolic disorder, affecting women of reproductive age groups, which shares various symptoms with thyroid dysfunctions. Despite it predisposition of aforesaid cohorts to autoimmunity, these etiologies have not adequately been studied in them. This study aimed to find out the prevalence of positive thyroid peroxidase antibodies among women with polycystic ovarian syndrome visiting an infertility clinic at a tertiary care centre.

Methods

This was a cross-sectional study conducted at a tertiary care centre among patients visiting the infertility clinic at the Department of Obstetrics and Gynaecology from 21 September 2022 to 21 February 2023. Biochemical analysis of thyroid hormones, gonadal hormones, anti-mullerian hormone and thyroid peroxidase antibody were done in Abbott ARCHITECT ci4100 and SNIBE Maglumi 800 autoanalyzer. A convenience sampling method was used. The point estimate was calculated at a 95% Confidence Interval.

Results

Among 70 participants, thyroid peroxidase antibody was positive in 16 (22.86%) (13.02-32.69, 95% Confidence Interval). The mean age of the patients was 28.25±5.26 years. In the individuals with thyroid-stimulating hormone below 2.5 mIU/l, 5 (31.25%) had positive thyroid peroxidase antibody titre.

Conclusions

The prevalence of positive thyroid peroxidase antibodies among women with polycystic ovarian syndrome is similar to other studies done in similar settings. Regular monitoring of thyroid peroxidase antibodies is recommended in these women to guide conception in order to evade inevitable adverse pregnancy outcomes.

Keywords

anti-thyroid autoantibodies; autoimmunity; infertility; prevalence; polycystic ovary syndrome.

The role of the thyroid in polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is the most common endocrine and metabolic disease in women of childbearing age and can cause metabolic disorder, infertility, and increased anxiety and depression; as a result, it can seriously affect the physical and mental health of fertile women. PCOS is a highly clinically heterogeneous disease with unclear etiology and pathogenesis, which increases the difficulty of treatment. The thyroid gland has complex regulatory effects on metabolism, reproduction, and emotion, and produces hormones that act on almost all cells of the human body. The clinical manifestations of PCOS are similar to some thyroid diseases. Furthermore, some thyroid diseases, such as subclinical hypothyroidism (SCH), not only increase the incidence rate of PCOS, but also exacerbate its associated metabolic abnormalities and reproductive disorders. Interestingly, PCOS also increases the incidence of some thyroid diseases. However, the role of the thyroid in PCOS remains unclear. This review is intended to thoroughly explore the critical role of the thyroid in PCOS by summarizing the comorbidity of PCOS and thyroid diseases and their combined role in metabolic disorders, related metabolic diseases, and reproductive disorders; and by analyzing the potential mechanism through which the thyroid influences the development and progression of PCOS and its symptoms. We hope this review will provide a valuable reference for the role of the thyroid in PCOS.

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.

Analysis of the effect of hashimoto's thyroiditis and insulin resistance on ovarian volume in patients with polycystic ovary syndrome

OBJECTIVE

In this study, patients were divided into two groups. Patients with polycystic ovary syndrome (PCOS) and patients with polycystic ovary syndrome + Hashimoto's Thyroid (PCOS + HT). The effect of insulin resistance on ovarian volume in patients divided into two groups and the change in ovarian volume with the addition of HT to PCOS will be investigated.

MATERIAL AND METHODS

46 PCOS patients and 46 PCOS patients diagnosed with HT were included in this study. A detailed medical history was taken from all participants. Polycystic ovary image was evaluated as below or above 10 ml and antral follicles were counted by transvaginal ultrasound. Insulin resistance of the patients was evaluated according to the fasting insulin (HOMA) index.

RESULTS

Insulin resistance was found to be associated with fasting insulin, HOMA index, body mass index and right ovarian volume in patients diagnosed with PCOS. Among the patients diagnosed with PCOS + HT, insulin resistance was found to be significantly correlated with fasting insulin, HOMA index, (BMI), (SHBG) and left ovarian volume. An increase in right ovarian volume was found in 37.5% of patients with PCOS without insulin resistance and in 76.3% of patients with insulin resistance. An increase in left ovarian volume was found in 35.7% of patients without insulin resistance diagnosed with PCOS + HT and in 68.8% of patients with insulin resistance.

CONCLUSIONS

This study shows that ovarian volume should be evaluated in every PCOS patient in order to predict insulin resistance, which causes long-term metabolic diseases, and that all PCOS patients with increased ovarian volume should be investigated for insulin resistance. In addition, it has been observed that insulin resistance affects left ovarian volume in patients with PCOS + HT, whereas insulin resistance affects the volume of the right ovary more in patients with PCOS. At least one ovary has been found to be affected by long-term metabolic diseases. While there was a greater increase in ovarian volume with the addition of insulin resistance, no significant change was observed in the number of patients with increased ovarian volume (PCOS-58, PCOS + HT-57) with the addition of HT finding.

Raised Thyroid-Stimulating Hormone in Girls with Polycystic Ovary Syndrome: Effects of Randomized Interventions

INTRODUCTION

Polycystic ovary syndrome (PCOS) in women associates with raised levels of circulating thyroid-stimulating hormone (TSH) and with high rates of gestational complications. A low range of preconception TSH is followed by low rates of gestational complications. It is unknown whether TSH levels are elevated in adolescents with PCOS and, if so, whether traditional or exploratory treatments can lower them into safe preconception range. We investigated TSH in nonobese adolescents with PCOS, including the effects of randomized interventions.

METHODS

Morning TSH was a safety marker in randomized pilot studies comparing the effects of an oral contraceptive (OC) versus those of a low-dose combination of spironolactone-pioglitazone-metformin (SPIOMET) in nonobese adolescents with PCOS. A post hoc analysis compared TSH levels in PCOS (N = 62) versus controls, TSH changes on treatment (for 1 year), and TSH levels posttreatment (for 1 year).

RESULTS

Mean TSH levels were higher in PCOS patients than in control girls (p < 0.01). On-treatment TSH levels diverged (p < 0.001), remaining elevated on OC, and descending swiftly on SPIOMET, well into safe preconception range. Posttreatment TSH levels were stable in both subgroups. On-treatment changes of circulating TSH associated to those of liver fat (R = 0.307, p = 0.017).

CONCLUSION

The endocrine signature of early PCOS is herewith extended to include modestly raised levels of circulating TSH; the normalizing effects of SPIOMET intervention in nonobese adolescents with PCOS are herewith extended to include on- and posttreatment TSH.

High frequency of autoimmune thyroiditis in euthyroid girls with premature adrenarche

Objective

The purpose of this study was to investigate the frequency of autoimmune thyroiditis (AT) among euthyroid prepubertal girls presenting with premature adrenarche (PA). We also aimed to identify the clinical, metabolic, and endocrine profile of girls with AT and concurrent PA and compare them to girls with AT without PA, PA alone and healthy controls.

Methods

Ninety-one prepubertal girls aged 5-10 years, who attended our department for AT, PA and normal variants of growth and puberty were recruited for the study: 73 girls had PA, 6 AT without PA and 12 were referred for investigation of growth. All girls underwent clinical examination, detailed biochemical and hormonal screen. Standard dose Synachten stimulation test (SDSST) and oral glucose tolerance test (OGTT) were performed in all girls with PA. The whole study population was divided in 4 groups: Group PA-/AT+ included 6 girls with AT without PA; Group PA+/AT- PA subjects without AT; Group PA+/AT+ girls with PA and concomitant AT; Group PA-/AT- twelve healthy girls without PA nor AT (controls).

Results

Among 73 girls presenting with PA 19 had AT (26%). BMI, systolic blood pressure (SBP) and the presence of goiter significantly differed between the four groups (p = 0.016, p = 0.022 and p < 0.001, respectively). When comparing hormonal parameters among the four groups significant differences were found in leptin (p = 0.007), TSH (p = 0.044), anti-TPO (p = 0.002), anti-TG (p = 0.044), IGF-BP1 (p = 0.006), Δ4-Α (p = 0.01), DHEA-S (p = <0.001), IGF-1 (p = 0.012) and IGF-BP3 (p = 0.049) levels. TSH levels were significantly higher in Group PA+/AT+ compared to PA+/AT- and PA-/AT- (p = 0.043 and p = 0.016, respectively). Moreover, girls with AT (Groups PA-/AT+ and PA+/AT+) had higher TSH levels than those in Group PA+/AT- (p = 0.025). Girls in Group PA+/AT + showed higher cortisol response at 60 min post-SDSST than girls in Group PA+/AT- (p = 0.035). During the OGTT, insulin concentrations at 60 min were significantly higher in Group PA+/AT + compared to Group PA+/AT- (p = 0.042).

Conclusion

A high frequency of AT among euthyroid prepubertal girls with PA was observed. The combination of PA with AT even in euthyroid state may be associated with a greater degree of insulin resistance, than PA alone.

Influence of Subclinical Hypothyroidism on Women With Polycystic Ovary Syndrome: A Literature Review

Subclinical hypothyroidism (SCH) is a commonly encountered condition in women with polycystic ovary syndrome (PCOS). Nevertheless, it is unclear whether SCH has any potential impact on the metabolic and reproductive profiles of women with PCOS. Hence, this literature review explores and establishes the link between these two conditions. In women with PCOS, SCH was found to aggravate insulin resistance and dyslipidemia. It was also linked to hormonal imbalances leading to higher infertility rates among the PCOS-SCH group. Therefore, women with PCOS must be screened for thyroid function frequently and managed accordingly.

Economic and Cardiometabolic Risk Factors Are Predictors of Lower Thyroid Stimulating Hormone (TSH) Levels in Hispanic/Latinx Adults with Euthyroidism-A Community-Based Study

Thyroid hormone abnormalities are among the most common endocrine disorders comorbidly suffered alongside metabolic syndrome and type 2 diabetes mellitus (T2DM), and within the euthyroid range they may also impact other outcomes, such as mood disorders. This study aimed to observationally examine the relationship between TSH and social determinants of health and clinical measures in a euthyroid Hispanic/Latinx patient sample with a diagnosis of anxiety and/or depression disorders from a community health clinic. A needs assessment was completed using a random sample of 100 de-identified medical records of individuals who received free medical care, including mental health, at a community-based clinic. Those with low normal TSH (<2 mIU/L) compared with high normal TSH (≥2 mIU/L) had a greater odds of food insecurity (p = 0.016) and being at 100% of the federal poverty level (p = 0.015). The low normal TSH group had significantly higher fasting glucose (p = 0.046), hemoglobin A1c (p = 0.018), and total cholesterol (p = 0.034) compared with the high normal TSH group. In those with T2DM, individuals with low normal TSH had six-times greater odds of having high fasting glucose (p = 0.022) and high hemoglobin A1c (p = 0.029). These relationships warrant further study, to inform future public health policies and follow-up care for underserved and vulnerable communities.

Association of Subclinical Hypothyroidism with Present and Absent Anti-Thyroid Antibodies with PCOS Phenotypes and Metabolic Profile

BACKGROUND

Polycystic ovary syndrome (PCOS) and subclinical hypothyroidism (SCH) often coexist, but implications of the co-occurrence of two disorders have not yet been established. The objective is to conclude whether SCH with present or absent anti-thyroid antibodies (ATA) impacts on the PCOS phenotype and alters biochemical or clinical parameters.

METHODS

A retrospective cohort study was conducted in a tertiary reference center. Clinical and biochemical parameters of women with PCOS were analyzed.

RESULTS

A total of 367 women with PCOS were included in the study, 114 (31.1%) of whom were diagnosed with SCH and 16 (4.4%) with autoimmune thyroiditis (AIT). Among all parameters studied, the strongest relationship with SCH was confirmed for insulin resistance and dyslipidemia. SCH was an independent risk factor for insulin resistance. In SCH the additional presence of ATA did not exacerbate the metabolic disorders. There was no significant association of any PCOS phenotype with SCH, nor with the presence of circulating ATA. There was no significant difference in hormonal parameters and mFerriman-Gallwey scale score between women with PCOS with and without SCH.

CONCLUSIONS

SCH alters metabolic, but not hormonal, parameters in PCOS. The diagnosis of SCH does not exclude the diagnosis of PCOS. The potential effect of positive ATA was insignificant.

Spatial clustering and meso-scale correlates of thyroid disorder among women in India: evidence from the National Family Health Survey (2015–16)

Purpose

Thyroid disorders are a major public health burden. Generally, women exhibit higher differentials in the prevalence of these disorders. This study focuses on the socio-economic and behavioural correlates of thyroid disorders along with their spatial clustering among women of reproductive age in India.

Methods

The study uses dataset from the fourth National Family Health Survey (NFHS-4) carried out in 2015–16 to assess self-reported thyroid disorders. Poor–rich ratio (PRR) and concentration index (CI) were used to study the variation in thyroid disorder among women arising out of economic inequality. Moran’s I statistics and bivariate local spatial autocorrelation (BiLISA) maps were used to understand spatial dependence and clustering of thyroid disorder. Spatial lag and error models were applied to examine the correlates of the disorder.

Results

Thyroid disorder prevalence was higher among women from socio-economically better-off households. Adjusted effects showed that users of iodized salt were 1.14 times more likely to suffer from a thyroid disorder as compared to non-users, which is contrary to the general belief that a higher percentage of consumption of iodide salt leads to a lower prevalence of thyroid disorder. A higher autoregressive coefficient (0.71) indicated significantly higher spatial clustering in thyroid disorders.

Conclusions

The prevalence of thyroid disorder in India depends appreciably on spatial and various ecological factors. Sedentary lifestyles among women may be aggravating diseases, which has strong linkage with thyroid disorders. It is strongly recommended to effectively integrate universal salt iodization with activities geared towards the elimination of iodine deficiency disorders.

The relationships between thyroid-stimulating hormone level and insulin resistance, glucose effectiveness, first- and second-phase insulin secretion in Chinese populations

Increased insulin resistance (IR); decreased glucose effectiveness (GE); and both first-and second phase of insulin secretion (FPIS, SPIS) have always been important factors for the development of type 2 diabetes. Therefore, in this study, we evaluated the relationships between thyroid-stimulating hormone (TSH) and these 4 factors in adult Chinese. We randomly enrolled 24,407 men and 24,889 women between 30 and 59 years old. IR, FPIS, SPIS and GE were measured with the equations built by our group. IR = log (1.439 + 0.018 × sex - 0.003 × age + 0.029 × BMI - 0.001 × SBP + 0.006 × DBP + 0.049 × TG - 0.046 × HDLC - 0.0116 × FPG) × 10 ^3.333. FPIS = 10 [1.477 - 0.119 × FPG + 0.079 × BMI - 0.523 × HDLC]. SPIS = 10 [-2.4 - 0.088 × FPG + 0.072 × BMI]. GE = (29.196 - 0.103 × age - 2.722 × TG - 0.592 × FPG) ×10 ^−3. The t test was performed to evaluate the differences between normal and diabetic groups. To evaluate the differences of the mean values of the 4 groups, from the highest to the lowest levels of TSH, we used a one-way analysis of variance. Age, high density lipoprotein-cholesterol and GE were higher in women. On the other hand, body mass index, blood pressure, low density lipoprotein-cholesterol, triglyceride, FPIS, SPIS and IR were higher in men. TSH was positively related to IR, FPIS, and SPIS and negatively related to GE. According to the r values, the tightest relationship was between TSH and IR, followed by GE, FPIS and SPIS. In conclusion, our data showed that IR, FPIS, and SPIS were positively related to the TSH level in middle-aged Chinese, whereas GE was negatively related. In both genders, IR had the tightest association followed by GE, FPIS, and SPIS.

A Comparative Study on Insulin Secretion, Insulin Resistance and Thyroid Function in Patients with Polycystic Ovary Syndrome with and without Hashimoto's Thyroiditis

OBJECTIVE

The incidence of Hashimoto's thyroiditis (HT) in patients with polycystic ovary syndrome (PCOS) is significantly higher than in normal controls, and there is a risk of more severe metabolic symptoms when the two diseases occur together. This study compares insulin secretion, insulin resistance (IR) and thyroid function in patients with PCOS with and without HT.

METHODS

A total of 164 patients (52 patients with HT (HT+) and 112 patients without HT diagnosed PCOS at our hospital were enrolled for testing of oral glucose tolerance, insulin release, thyroid function, the presence of thyroglobulin and thyroid peroxidase antibodies, and blood lipid levels.

RESULTS

Patients with PCOS and HT had higher insulin secretion and IR levels than those without HT, while free thyroxine and thyrotropin levels were significantly lower. The ratio of free thyroxine to thyrotropin was higher in patients with HT.

CONCLUSION

HT may related with IR and relatively low thyroid function in patients with PCOS. Thus, thyroid function and autoimmune status in patients with PCOS should be evaluated in clinical practice.

The Influence of Treated and Untreated Subclinical Hypothyroidism on Metabolic Profile in Women with Polycystic Ovary Syndrome

BACKGROUND

Polycystic ovary syndrome (PCOS) and hypothyroidism are the most common endocrinological disorders among women of reproductive age. Since hypothyroidism occurs more frequently in PCOS patients, it is vital to explain its clinical impact.

AIM

To evaluate the impact of subclinical hypothyroidism (SCH) and its treatment on the metabolic profile of patients with PCOS.

METHODS

190 women with PCOS phenotype A were enrolled in the case-control study. They were divided into three groups: 38 women with PCOS and subclinical hypothyroidism, 76 women with PCOS and SCH under thyroid replacement therapy, and 76 women with PCOS and normal thyroid function (control group). Serum lipids, fasting glucose, and insulin, as well as oral glucose tolerance tests were performed.

RESULTS

In the analyzed parameters, there were no statistic differences between the groups in relation to thyroid function. BMI turned out to be the main factor dividing the patients in terms of serum lipids, fasting glucose, fasting insulin, and oral glucose tolerance test. TSH was associated with total cholesterol and LDL cholesterol levels, whereas BMI has a dominant impact on HDL cholesterol, triglycerides, glucose, and insulin resistance.

CONCLUSIONS

SCH is associated with mild lipid serum alterations in women with PCOS, but it is BMI to have a dominant impact on glucose and insulin. It seems that treatment of SCH in PCOS does not significantly alter lipid and glucose metabolism.

Genome-wide meta-analysis identifies novel loci associated with free triiodothyronine and thyroid-stimulating hormone

PURPOSE

Thyroid hormones are essential for the normal function of almost all human tissues, and have critical roles in metabolism, differentiation and growth. Free triiodothyronine (fT3), free thyroxine (fT4) and thyroid-stimulating hormone (TSH) levels are under strong genetic influence; however, most of the heritability is yet unexplained.

METHODS

In order to identify novel loci associated with fT3, fT4 and TSH serum levels we performed a genome-wide meta-analysis of 7 411 206 polymorphisms in up to 1731 euthyroid individuals from three Croatian cohorts from Dalmatia region: two genetically isolated island populations and one mainland population. Additionally, we also performed a bivariate analysis of fT3 and fT4 levels.

RESULTS

The EPHB2 gene variant rs67142165 reached genome-wide significance for association with fT3 plasma levels (P = 9.27 × 10^-9) and its significance was confirmed in bivariate analysis (P = 9.72 × 10^-9). We also found a genome-wide significant association for variant rs13037502 upstream of the PTPN1 gene and TSH plasma levels (P = 1.67 × 10^-8).

CONCLUSION

We identified a first genome-wide significant variant associated with fT3 plasma levels, as well as a novel locus associated with TSH plasma levels. These findings are biologically relevant and enrich our knowledge about the genetic basis of pituitary-thyroid axis function.

Clinical, Hormonal, and Metabolic Parameters in Women with Subclinical Hypothyroidism and Polycystic Ovary Syndrome: A Cross-Sectional Study

BACKGROUND

Polycystic ovary syndrome (PCOS) is the most common endocrinopathy in reproductive age women, yet its clinical presentation shares similarities with several other endocrine disorders such as thyroid disease. Hence, the objective of this study was to further evaluate this association by investigating the clinical, hormonal, and metabolic parameters between subclinical hypothyroidism (SCH) and PCOS.

METHODS

This is a cross-sectional study conducted in a tertiary care clinic at Cleveland, Ohio, USA. A total of 137 women diagnosed with PCOS by Rotterdam criteria were examined. SCH was defined as thyroid-stimulating hormone >2.5 mIU/L in the absence of symptoms of overt hypothyroidism. The mean age, body mass index (BMI), fasting plasma glucose (FPG), glucose tolerance test, hemoglobin A1c, fasting insulin, a 2 hours insulin level after 75 g glucose load, cholesterol, LDL, HDL, and homeostatic model assessment (HOMA) were compared between women with and without SCH. Logistic regression was used to adjust for age and BMI.

RESULTS

Among 137 women with PCOS, 21.9% had SCH. Comparison groups were similar in both age and BMI and there was no difference in the mean values of all endocrine and metabolic parameters tested. However, abnormal FPG levels (OR 3.01; CI: 1.12-8.07. p = 0.03) and abnormal HOMA (OR 3.7; CI: 1.14-12.00. p = 0.03) were more likely in women who had SCH than in women without SCH independent of age and BMI.

CONCLUSIONS

Women with PCOS and SCH are more likely to have impaired FPG values and impaired insulin sensitivity even after adjusting for age and BMI. Hence, close monitoring of PCOS patients for SCH may be beneficial.

Thyroid-Stimulating Hormone Levels Are Positively Associated with Insulin Resistance

BACKGROUND It has been reported that overt and mild thyroid dysfunctions are associated with insulin resistance (IR). We performed this retrospective study to evaluate the relationships between thyroid-stimulating hormone (TSH) levels within the reference range and IR. MATERIAL AND METHODS A total of 447 outpatients were enrolled in this study: 298 with type 2 diabetes mellitus and 149 nondiabetic individuals. Based on a cutoff HbA1c value of 7%, diabetic patients were additionally divided into 2 groups: a high-HbA1c group (n=240) and a low-HbA1c group (n=58). The relationships of TSH levels and HOMA-IR were computed using linear regression models. RESULTS TSH levels were positively and linearly associated with HOMA-IR in both the nondiabetic and diabetic groups (r=0.210, p=0.011 and r=0.451, p<0.001), as well as in the high- and low-HbA1c groups (r=0.507, p<0.001 and r=0.259, p=0.048). A better correlation between TSH levels and HOMA-IR was found in the diabetic group and in the high-HbA1c group when compared with the nondiabetic group and the low-HbA1c group, respectively. Linear regression analysis showed that TSH levels were independently associated with HOMA-IR (p=0.034, =0.049 and <0.001 in nondiabetic, low-, and high-HbA1c groups, respectively). CONCLUSIONS Our data suggest that TSH is independently associated with insulin resistance.

Subclinical Hypothyroidism Impact on the Characteristics of Patients with Polycystic Ovary Syndrome. A Meta-Analysis of Observational Studies

BACKGROUND/AIMS

Definitive polycystic ovary syndrome (PCOS) diagnosis should exclude thyroid dysfunctions. The purpose of the study is to examine the impact of subclinical hypothyroidism on the characteristics of PCOS patients.

METHODS

A meta-analysis of the published observational studies was conducted. Medline, Scopus, and Cochrane database search was performed to identify the studies that compared euthyroid PCOS and subclinical hypothyroidism (SCH)-PCOS patients. A total of 9 studies were selected, totalizing the inclusion of 1,537 euthyroid PCOS and 301 SCH-PCOS. The data were expressed as raw mean difference and standard error, using the random-effects model. Heterogeneity among studies was examined using the Cochran's test (Q) and I2 statistics.

RESULTS

Anthropometrical parameters were similar in both groups. Total cholesterol (TC) and triglyceride (TG) were higher in SCH-PCOS (p = 0.036 and p = 0.012). High-density lipoprotein cholesterol was lower in the SCH-PCOS group (p = 0.018). Fasting glucose was lower in euthyroid PCOS (p = 0.022). All androgen levels were similar in both group (p > 0.05 for all).

CONCLUSION

TC, TG and fasting glucose were higher in SCH-PCOS patients. Because of the heterogeneity among studies, some summarized results should be interpreted with caution. Consistent data for future studies addressing PCOS diagnosis are provided.

Intrauterine Zn Deficiency Favors Thyrotropin-Releasing Hormone-Increasing Effects on Thyrotropin Serum Levels and Induces Subclinical Hypothyroidism in Weaned Rats

Individuals who consume a diet deficient in zinc (Zn-deficient) develop alterations in hypothalamic-pituitary-thyroid axis function, i.e., a low metabolic rate and cold insensitivity. Although those disturbances are related to primary hypothyroidism, intrauterine or postnatal Zn-deficient adults have an increased thyrotropin (TSH) concentration, but unchanged thyroid hormone (TH) levels and decreased body weight. This does not support the view that the hypothyroidism develops due to a low Zn intake. In addition, intrauterine or postnatal Zn-deficiency in weaned and adult rats reduces the activity of pyroglutamyl aminopeptidase II (PPII) in the medial-basal hypothalamus (MBH). PPII is an enzyme that degrades thyrotropin-releasing hormone (TRH). This hypothalamic peptide stimulates its receptor in adenohypophysis, thereby increasing TSH release. We analyzed whether earlier low TH is responsible for the high TSH levels reported in adults, or if TRH release is enhanced by Zn deficiency at weaning. Dams were fed a 2 ppm Zn-deficient diet in the period from one week prior to gestation and up to three weeks after delivery. We found a high release of hypothalamic TRH, which along with reduced MBH PPII activity, increased TSH levels in Zn-deficient pups independently of changes in TH concentration. We found that primary hypothyroidism did not develop in intrauterine Zn-deficient weaned rats and we confirmed that metal deficiency enhances TSH levels since early-life, favoring subclinical hypothyroidism development which remains into adulthood.

MANAGEMENT OF ENDOCRINE DISEASE: The impact of subclinical hypothyroidism on anthropometric characteristics, lipid, glucose and hormonal profile of PCOS patients: a systematic review and meta-analysis

OBJECTIVE

Subclinical hypothyroidism (SCH) is encountered in 10-25% of women with PCOS. To date, it remains unclear whether this coexistence influences the severity of metabolic and hormonal profile of these patients. The purpose of our systematic review is to investigate this potential relation.

METHODS

We systematically searched Medline, Scopus, ClinicalTrials.gov, Cochrane Central Register of Controlled Trials (CENTRAL) and Google Scholar databases together with reference lists from included studies. All prospective and retrospective observational cohort studies that investigated the impact of subclinical hypothyroidism on hormonal and metabolic parameters of PCOS patients were included. The methodological quality of studies was assessed with the Ottawa-Newcastle criteria. Statistical meta-analysis was performed with the RevMan 5.3 software.

RESULTS

Twelve studies were finally included in the present review, which enrolled 2341 PCOS patients. Among them, 577 had subclinical hypothyroidism, whereas the remaining 2077 were PCOS women with normal thyroid function. The presence of SCH significantly affected HDL (MD -3.92 mg/dL 95% CI: -6.56, -1.29) and triglycerides levels (26.91 mg/dL 95% CI: -3.79, 50.02). HOMA-IR was also affected (MD 0.82 95% CI: 0.15, 1.50). On the other hand, LDL, fasting glucose and 2-h OGTT were not influenced. Similarly, prolactin, FSH, LH, LH/FSH ratio and sex hormone-binding globulin remained unaffected.

CONCLUSION

Subclinical hypothyroidism does not influence the hormonal profile of women with PCOS. On the other hand, it results in mild metabolic abnormalities, which are not clinically important in a short-term setting.

Insulin Resistance: Any Role in the Changing Epidemiology of Thyroid Cancer?

In the past few decades, the incidence of thyroid cancer (TC), namely of its papillary hystotype (PTC), has shown a steady increase worldwide, which has been attributed at least in part to the increasing diagnosis of early stage tumors. However, some evidence suggests that environmental and lifestyle factors can also play a role. Among the potential risk factors involved in the changing epidemiology of TC, particular attention has been drawn to insulin-resistance and related metabolic disorders, such as obesity, type 2 diabetes, and metabolic syndrome, which have been also rapidly increasing worldwide due to widespread dietary and lifestyle changes. In accordance with this possibility, various epidemiological studies have indeed gathered substantial evidence that insulin resistance-related metabolic disorders might be associated with an increased TC risk either through hyperinsulinemia or by affecting other TC risk factors including iodine deficiency, elevated thyroid stimulating hormone, estrogen-dependent signaling, chronic autoimmune thyroiditis, and others. This review summarizes the current literature evaluating the relationship between metabolic disorders characterized by insulin resistance and the risk for TC as well as the possible underlying mechanisms. The potential implications of such association in TC prevention and therapy are discussed.

Subclinical hypothyroidism is associated with metabolic syndrome and clomiphene citrate resistance in women with polycystic ovary syndrome

BACKGROUND

To evaluate the possible relationship between subclinical hypothyroidism (SCH) and metabolic syndrome (MS) and the response to clomiphene citrate (CC) stimulation in women with polycystic ovary syndrome (PCOS).

METHODS

One hundred and ninety-six women with PCOS were divided into two groups: (1) the SCH group with 92 patients; (2) the euthyroid (EU) group with 104 patients. Physical characteristics and metabolic parameters as well as the reaction to CC stimulating test were compared between these two groups.

RESULTS

(1) In the SCH group, significantly higher body mass index, Ferriman-Gallwey score, serum triglyceride, insulin and glucose of oral glucose tolerance test, homeostatic model assessment-insulin resistance (HOMA-IR) and significantly lower serum high-density lipoprotein cholesterol was observed in comparison with those in the EU group (p < 0.05). (2) The prevalence of CC resistance (30.4%), IR (43.5%) and MS (34.8%) in the SCH group was significantly higher than that in the EU group (p < 0.05).

CONCLUSIONS

SCH was found associated with IR, MS and CC resistance in women with PCOS. PCOS patients with SCH may have a poorer treatment response to ovulation induction with CC.

Maternal subclinical hypothyroidsm and gestational diabetes mellitus: a meta-analysis

OBJECTIVE

The association between subclinical hypothyroidism (SCH) and gestational diabetes mellitus (GDM) is controversial. This review evaluates whether the risk of GDM is different in pregnant women with SCH compared to euthyroid pregnant women.

METHODS

A computerized search of the MEDLINE and EMBASE databases was conducted from their inceptions to July 2013 and was complemented with the perusal of the reference sections of the retrieved articles. Prespecified criteria were applied to assess eligibility, and standard meta-analytic methodology was employed for evidence synthesis.

RESULTS

Six cohort studies, reporting data on 35,350 pregnant women (1,216 women with SCH), were identified. The risk of GDM in pregnant women with SCH was found to be substantially higher compared to euthyroid pregnant women (5 studies, pooled unadjusted odds ratio [OR]: 1.35, 95% confidence interval [CI]: 1.05-1.75, I2: 41%, Harbord test P = .44). Similarly, the risk of GDM was estimated to be significantly higher in pregnant women with SCH when using adjusted estimates (3 studies, pooled adjusted OR: 1.39, 95% CI: 1.07-1.79, I2: 0%). Neither finding remained significant in sensitivity analyses.

CONCLUSION

A modestly increased risk of GDM might be present in pregnant women with SCH compared to euthyroid pregnant women. Assuming a 5% baseline risk of GDM and that SCH increases the risk of GDM by 50% (in odds) compared to a euthyroid population, then there would be 1 extra case of GDM in every 43 pregnant women with SCH. This preliminary finding warrants further investigation.

Subclinical Hypothyroidism in PCOS: Impact on Presentation, Insulin Resistance, and Cardiovascular Risk

Aim of Study. To assess status of thyroid function and thyroid disorders particularly subclinical hypothyroidism (SCH) in subjects with polycystic ovarian syndrome (PCOS) and impact of SCH on various clinical and biochemical parameters and cardiovascular risk in PCOS. Methods. Hundred females diagnosed with PCOS as per Rotterdam criteria and 100 normal controls were recruited and were subjected to elaborate anthropometric, clinical, and biochemical assessment. Results. Notable findings included significantly higher frequency of subjects with subclinical hypothyroidism (p = 0.0002), autoimmune thyroiditis (p < 0.001), and goitre (p = 0.02) in polycystic ovarian syndrome subjects compared to control subjects. Further SCH PCOS subjects were found to harbor significantly higher HOMA-IR (p < 0.05) and frequency of subjects with dyslipidemia (p < 0.05) compared to both euthyroid PCOS and euthyroid control subjects. Though frequency of subjects with cardiovascular risk factors was higher in SCH PCOS group than euthyroid PCOS group, it failed to reach statistical significance. Conclusion. We concluded that PCOS is associated with high incidence of SCH and AIT compared to normal population and SCH poses increased risk of cardiovascular disorder in PCOS.

IS SUBCLINICAL HYPOTHYROIDISM IN PATIENTS WITH POLYCYSTIC OVARY SYNDROME ASSOCIATED WITH BMI?

Objective

To investigate the impact of body weight on the subclinical hypothyroidism observed in patients with PCOS.

Methods

The study included 95 normal weight (Group-1) and 122 overweight or obese women (Group-2) with PCOS. The control group consisted of age and BMI matched healthy individuals and grouped as normal weight (n: 66, Group-3) and overweight or obese (n: 65, Group-4. Women with chronic disease such as overt thyroid dysfunction, late-onset adrenal hyperplasia, and diabetes were excluded from the study. Plasma glucose and lipid profile, thyroid hormones, insulin, FSH, LH, total testosterone, estradiol, progesterone and DHEA-S were measured.

Results

While fasting glucose was similar, insulin and HOMA-IR were higher in Group-2 and Group-4 (p: 0.001). The groups were similar with respect to FSH, Estradiol, prolactine, DHEAS. While total testosterone and LH levels were higher (ptestosterone: 0,009), progesterone was lower in both PCOS groups (pprogesterone: 0.041). Free T3, free T4, thyroid antibodies were similar between the groups, but the prevalence of subclinical hypothyroidism was greater in Group-2 and -4 than in Group-1 and -3 (p: 0.044). TSH was only correlated with BMI (r: 0.122, p: 0.02).

Conclusion

The increased prevalence of subclinical hypothyroidism in women with PCOS might be the result of increased BMI.

Impact of elevated thyroid-stimulating hormone levels in polycystic ovary syndrome

The objective of this study was to analyse the impact of elevated thyroid-stimulating hormone (TSH) levels on the metabolic and endocrine phenotype in 583 women with polycystic ovary syndrome (PCOS). Endocrine and metabolic parameters were measured in all patients and compared between women with and without elevated TSH levels. Of the 583 women with PCOS, 125 women (21.4%) had thyroid disturbances (thyroid replacement therapy: 109 women, subclinical hypothyroidism: 16 women). Patients with elevated TSH levels had significantly increased fasting insulin, area under the curve-insulin, homeostatic model assessment-insulin resistance, and total cholesterol (TC)/high-density lipoprotein cholesterol (HDL) ratio and lower free thyroxin, insulin sensitivity and HDL (p < 0.05 for all). Euthyroid PCOS women with thyroid hormone substitution showed significant differences in TSH, age, body mass index, HDL and systolic blood pressure compared to those without hormone replacement therapy (p < 0.05 for all). We conclude that hypothyroid disturbances and elevated TSH levels are common findings in PCOS, which are associated with an adverse metabolic profile. Therefore, women with diagnosed PCOS should be screened for thyroid dysfunction.

Serum Concentrations of Ghrelin and Leptin according to Thyroid Hormone Condition, and Their Correlations with Insulin Resistance

BACKGROUND

Thyroid hormones can influence energy metabolism and insulin sensitivity via their interaction with adipocytokines and gut hormones. The aims of this study were to evaluate differences in serum ghrelin and leptin concentrations according to thyroid hormone levels, and to investigate the correlation of insulin resistance.

METHODS

A total of 154 patients (57 hyperthyroid patients, 61 euthyroid patients, and 36 hypothyroid patients; mean age, 47.9 years) were enrolled. Serum leptin, ghrelin, and insulin levels were measured and insulin resistance was calculated using the formula of the homeostasis model assessment of insulin resistance (HOMA-IR).

RESULTS

There were no differences in mean concentrations of ghrelin or leptin among the three groups. There were no significant differences in insulin levels between the groups (P=0.06), although hyperthyroid patients had borderline statistically significantly higher levels of insulin than did euthyroid subjects by post hoc test (26.4 μIU/mL vs. 16.1 μIU/mL, P=0.057). Regarding HOMA-IR index, the mean levels were highest in the hyperthyroid group among those of the three groups (hyperthyroid vs. euthyroid vs. hypothyroid, 6.7 vs. 3.8 vs. 4.4, P=0.068). Plasma levels of ghrelin were significantly negatively correlated with age, insulin, glucose, body mass index (BMI), and HOMA-IR. Plasma levels of leptin showed significant positive correlation with BMI and triglyceride. There were no significant correlations among thyroid hormone, thyrotropin, ghrelin, leptin, or insulin.

CONCLUSION

The present study found that serum ghrelin, leptin, and insulin levels didn't differ according to thyroid function conditions. Further studies with larger numbers of patients are required to establish a direct relationship between plasma ghrelin, leptin, and thyroid hormone.

Thyroid disorders and polycystic ovary syndrome: An emerging relationship

As the prevalence of these endocrine dysfunctions increases, the association of polycystic ovary syndrome (PCOS) and autoimmune thyroid disease is increasingly being recognised. While the causality of this association is still uncertain, the two conditions share a bidirectional relationship. The exact nature of this link has not been elucidated yet. Both syndromes share certain common characteristics, risk factors, and pathophysiological abnormalities. Simultaneously, certain etiopathogenetic factors that operate to create these dysfunctions are dissimilar. Polycystic appearing ovaries are a clinical feature of hypothyroidism, though hypothyroidism should be excluded before diagnosing PCOS. Adiposity, increased insulin resistance, high leptin, evidence of deranged autoimmunity, all of which are present in both disease states, seem to play a complex role in connecting these two disorders. This brief communication explores the nature of the relationship between PCOS and hypothyroidism. It reviews current data and analyses them to present a unified pathophysiological basis, incorporating these complex relationships, for the same.

Polycystic ovary syndrome and chronic autoimmune thyroiditis

INTRODUCTION

Polycystic ovary syndrome (PCOS) has been associated with an autoimmune origin, either per se or favoring the onset of autoimmune diseases, from a stimulatory action on the inflammatory response. Thus, autoimmune thyroiditis (AIT) could be more prevalent among women with PCOS.

OBJECTIVE

To evaluate the prevalence of AIT in women with PCOS.

STUDY DESIGN

It was a cross-sectional study, in a tertiary center, including 65 women with PCOS and 65 women without this condition. Clinical and laboratory parameters were evaluated and a thyroid ultrasound scan was performed. Levels of thyroid-stimulating hormone (TSH), free thyroxine (FT4), free triiodothyronine (FT3), anti-thyroid peroxidase (anti-TPO) antibodies, anti-thyroglobulin (anti-TG) antibodies, and thyroid ultrasound findings were evaluated.

RESULTS

The prevalence of subclinical hypothyroidism (SCH) in women with PCOS was 16.9% and 6.2% in the non-PCOS group. AIT was more common in the PCOS group compared with the non-PCOS group (43.1% versus 26.2%). But, when it was adjusted by weight and insulin resistance, the difference in the thyroiditis risk was not observed (OR 0.78, CI 0.28-2.16).

CONCLUSION

AIT risk was similar in the PCOS and the non-PCOS group. SCH are more common in women with PCOS, highlighting a need for periodic monitoring of thyroid function.

Mechanisms in endocrinology: thyroid and polycystic ovary syndrome

Thyroid disorders, especially Hashimoto's thyroiditis (HT), and polycystic ovary syndrome (PCOS) are closely associated, based on a number of studies showing a significantly higher prevalence of HT in women with PCOS than in controls. However, the mechanisms of this association are not as clear. Certainly, genetic susceptibility contributes an important part to the development of HT and PCOS. However, a common genetic background has not yet been established. Polymorphisms of the PCOS-related gene for fibrillin 3 (FBN3) could be involved in the pathogenesis of HT and PCOS. Fibrillins influence the activity of transforming growth factor beta (TGFβ). Multifunctional TGFβ is also a key regulator of immune tolerance by stimulating regulatory T cells (Tregs), which are known to inhibit excessive immune response. With lower TGFβ and Treg levels, the autoimmune processes, well known in HT and assumed in PCOS, might develop. In fact, lower levels of TGFβ1 were found in HT as well as in PCOS women carrying allele 8 of D19S884 in the FBN3 gene. Additionally, vitamin D deficiency was shown to decrease Tregs. Finally, high estrogen-to-progesterone ratio owing to anovulatory cycles in PCOS women could enhance the immune response. Harmful metabolic and reproductive effects were shown to be more pronounced in women with HT and PCOS when compared with women with HT alone or with controls. In conclusion, HT and PCOS are associated not only with respect to their prevalence, but also with regard to etiology and clinical consequences. However, a possible crosstalk of this association is yet to be elucidated.

Association between Lower Normal Free Thyroxine Concentrations and Obesity Phenotype in Healthy Euthyroid Subjects

We investigated whether thyroid function could identify obesity phenotype in euthyroid subjects. A cross-sectional analysis was performed among nondiabetic, euthyroid subjects. We stratified subjects into four groups by BMI and insulin resistance (IR). Of 6241 subjects, 33.8% were overweight or obese (OW/OB) and 66.2% were normal weight (NW). Free thyroxine (FT4) levels were negatively associated with body mass index, waist circumference, triglyceride, c-reactive protein, and HOMA-IR and positively with high-density lipoprotein cholesterol in both genders. In multivariate regression analysis, FT4 level, a continuous measurement, was negatively correlated with HOMA-IR (β = -0.155, P < 0.001 in men; β = -0.175, P < 0.001 in women). After adjustment for age, sex, metabolic, and life style factors, subjects in the lowest FT4 quartile had an odds ratio (OR) for IR of 1.99 (95% confidence interval 1.61-2.46), as compared to those in the highest quartile. The association between low FT4 and IR remained significant in both NW and OW/OB subgroups. In conclusion, low normal FT4 levels were independently related to IR in NW and OW/OB euthyroid subjects. Further studies are needed to investigate the mechanisms by which low FT4 levels are linked to high IR in euthyroid ranges.

Alterations in thyroid function among the different polycystic ovary syndrome phenotypes

The study evaluates the prevalence of subclinical thyroid dysfunction in infertile PCOS patients, according to the different PCOS phenotypes and to examine whether insulin sensitizers in insulin resistant (IR) PCOS patients may improve thyroid function. The study population consisted of all PCOS patients, attending the infertility and IVF unit of Department of Pediatrics, Obstetrics and Reproductive Medicine of University of Siena, Italy, and compared them to regularly cycling, healthy, infertile controls. Upon admission, blood was drawn from all patients during the early follicular phase, for complete hormonal and metabolic profiles. In IR-PCOS patients treated with insulin sensitizers, blood was drawn again after 6 months. PCOS patients had a significantly higher prevalence of subclinical thyroid dysfunction compared to infertile controls. While no significant association was detected between TSH value and the presence of hyperandrogenism, overweight and obese PCOS patients, as well as IR PCOS patients showed significantly higher prevalence of subclinical thyroid dysfunction. Moreover, among IR PCOS patients, 6 months treatment with insulin sensitizers significantly reduces TSH levels. Infertile PCOS patients have a high prevalence of subclinical thyroid dysfunction, which may be successfully treated in IR PCOS patients by insulin sensitizers.

Thyroglobulin autoantibodies: is there any added value in the detection of thyroid autoimmunity in women consulting for fertility treatment?

BACKGROUND

Thyroid autoimmunity (TAI) is frequent in infertile women, but to what extent thyroglobulin autoantibodies (Tg-Abs) contribute to TAI is unclear in the literature. The aims of the present study were to determine the prevalence of TAI in women consulting for fertility problems and to investigate the impact of isolated Tg-Abs, isolated thyroid peroxidase autoantibodies (TPO-Abs), and the presence of both autoantibody types on thyroid function. Furthermore, thyroid function was compared between women with and without TAI and between infertile and fertile women.

METHODS

A cross-sectional data analysis nested within an ongoing prospective cohort study was performed in order to determine the prevalence of TAI in unselected women consulting our tertiary referral center for reproductive medicine (CRM). The women underwent a determination of serum thyrotropin (TSH), free thyroxine (FT4), TPO-Abs, and Tg-Abs. The cause of infertility, age, body-mass index (BMI), and smoking habits were recorded.

RESULTS

The prevalence of TAI was 16% (163/992). In 8% of cases, both types of autoantibodies were present, in 5% isolated positive Tg-Abs were found, and 4% had isolated positive TPO-Abs (p=0.025 and p=0.003 respectively). The prevalence of TAI was significantly higher in infertile women as compared to that in fertile controls (19% vs. 13%; p=0.047). The median serum TSH level was significantly higher in the women with TAI and with isolated positive Tg-Abs compared to that in women without TAI (1.83 [1.44] and 1.90 [0.85] vs. 1.47 [0.94] mIU/L; p<0.001 respectively). The median FT4, age, BMI, and smoking habits were comparable between the study groups.

CONCLUSIONS

The prevalence of TAI was higher in infertile women as compared to fertile women consulting our CRM. Five percent of the women had isolated positive Tg-Abs and a significantly higher serum TSH compared to that in women without TAI.

Effect of different culture systems and 3, 5, 3'-triiodothyronine/follicle-stimulating hormone on preantral follicle development in mice

The mechanical method to isolate preantral follicle has been reported for many years. However, the culture systems in vitro are still unstable. The aim of this study was to analyze the effect of the culture system of mice preantral follicles on the follicular development in vitro. The results showed that the 96-well plate system was the most effective method for mice follicle development in vitro (volume change: 51.71%; survival rate: 89%, at day 4). Follicle-stimulating hormone (FSH) and Thyroid hormone (TH) are important for normal follicular development and dysregulation of hormones are related with impaired follicular development. To determine the effect of hormone on preantral follicular development, we cultured follicle with hormones in the 96-well plate culture system and found that FSH significantly increased preantral follicular growth on day 4. The FSH-induced growth action was markedly enhanced by T₃ although T₃ was ineffective alone. We also demonstrated by QRT-PCR that T₃ significantly enhanced FSH-induced up-regulation of Xiap mRNA level. Meanwhile, Bad, cell death inducer, was markedly down-regulated by the combination of hormones. Moreover, QRT-PCR results were also consistent with protein regulation which detected by Western Blotting analysis. Taken together, the findings of the present study demonstrate that 96-well plate system is an effective method for preantral follicle development in vitro. Moreover, these results provide insights on the role of thyroid hormone in increasing FSH-induced preantral follicular development, which mediated by up-regulating Xiap and down-regulating Bad.

Adipocytokines mark insulin sensitivity in euthyroid Hashimoto's patients

The relationship between inflammation, Hashimoto's thyroiditis (HT) and insulin resistance is still controversial. In this regard, a pretty complete evaluation of adipocytokines levels in patients with HT has not been performed so far. We assessed retinol binding protein-4 (RBP4), adipocyte-fatty acid binding protein (A-FABP), neutrophil gelatinase-associated lipocalin (NGAL) and tumor necrosis factor-α (TNFα) levels in 93 euthyroid HT patients and 51 healthy controls (CTL), also evaluating the possible correlation between adipocytokines levels and markers of insulin resistance. No significant differences between HT patients and CTL in fasting plasma glucose and insulin levels, and HOMA index were observed. HT patients had significantly higher RBP4, NGAL and A-FABP levels than CTL, while TNFα levels did not differ between the two groups. In HT patients, RBP4 was significantly related with fT3 and fT4 levels, while A-FABP with fT4 only. Moreover, in HT patients, either RBP4 or A-FABP was directly associated with plasma insulin and HOMA index. Circulating levels of these adipocytokines were not influenced by the presence of antithyroid peroxidase or antithyroglobulin autoantibodies or only one of them, neither by autoantibodies titer. In conclusion, euthyroid HT patients are characterized by a peculiar inflammatory response of the adipose tissue, apparently related to an early reduction in insulin sensitivity and to serum thyroid hormone levels, although within the normal range. These results suggest that HT patients with high RBP4 and A-FABP levels might deserve a particular attention, being potentially more exposed to develop insulin resistance and increased cardiovascular risk.

Common genetic variation in CYP1B1 is associated with concentrations of T₄, FT₃ and FT₄ in the sera of polycystic ovary syndrome patients

CYP1B1 encodes an estrogen enzyme that oxidizes 17β-estradiol to 4-hydroxyestradiol. The evidence demonstrates there may be a relationship between CYP1B1 and thyroid function. To date, no study has evaluated if genetic polymorphisms that regulate concentrations of serum FT3 and FT4 contribute to Polycyctic Ovary Syndrome (PCOS). To identify polymorphisms in the CYP1B1 locus associated with PCOS, we genotyped three common polymorphisms across the CYP1B1 locus in 226 patients. A test for association of common variants with susceptibility to PCOS was conducted in a large cohort of 609 subjects. The functional polymorphism CYP1B1 L432V (rs1056836) is associated with serum T4 (P = 0.003), serum FT3 (P < 0.001) and serum FT4 concentrations (P < 0.001). Our study provides the first evidence that genetic variants in CYP1B1 can be associated with serum T4, FT4 and FT3 levels in PCOS. These findings imply novel pathophysiological links between the CYP1B1 locus and thyroid function in PCOS.

Subclinical hypothyroidism in young women with polycystic ovary syndrome: an analysis of clinical, hormonal, and metabolic parameters

OBJECTIVE

To analyze the relationship between selected clinical and metabolic parameters in young women with polycystic ovary syndrome (PCOS) and normal thyroid function or subclinical hypothyroidism (SCH).

DESIGN

A cross-sectional cohort study.

SETTING

Tertiary care clinic.

PATIENT(S)

Women diagnosed with PCOS according to the Rotterdam criteria (n = 168).

INTERVENTION(S)

Clinical, hormonal, and metabolic parameters were evaluated. SCH was defined as TSH levels of 4.5-10 mIU/L.

MAIN OUTCOME MEASURE(S)

Separately, PCOS and SCH exert adverse effects on metabolic parameters; however, in conjunction their effect is unclear. This study evaluated whether SCH in women with PCOS affects clinical, hormonal, and metabolic parameters.

RESULT(S)

The mean age of the 168 women was 24 ± 5.8 years. Mean body mass index was 33.4 ± 8.2 kg/m(2). Thyroid function was normal in 149 women, and 19 had SCH. Only serum low-density lipoprotein cholesterol and PRL levels were significantly higher in the women with SCH (122.6 ± 25.6 mg/dL and 17.7 ± 7.7 ng/mL, respectively) compared with those with normal thyroid function (105.6 ± 33 mg/dL and 14 ± 10.3 ng/mL, respectively).

CONCLUSION(S)

In young women with PCOS, SCH is associated with higher low-density lipoprotein cholesterol levels, albeit with no changes in other lipid profile parameters, insulin resistance, or phenotypic manifestations. This study adds to current evidence supporting an association between PCOS and SCH.

Is subclinical hypothyroidism contributing dyslipidemia and insulin resistance in women with polycystic ovary syndrome?

We aimed to analyze lipid parameters and determine the need for a 2-hour oral glucose tolerance test (OGTT) for the identification of IR and impaired glucose tolerance test (IGT) in subclinical hypothyroidism (SCH) women with and without polycystic ovary syndrome (PCOS). 20 patients with PCOS and SCH consisted of Group I and 39 patients with PCOS and normal thyroid function consisted of Group II and 53 healthy women with normal thyroid function consisted of Group III. Triglyceride levels were 143.26 ± 99.86 mg/dL in group 1 and 88.56 ± 37.56 mg/dL in group 2 and 83.71 ± 31.94 mg/dL in group 3 which were statistically significant. Total cholesterol, HDL- cholesterol, LDL-cholesterol were found similar between the groups. Fasting insulin levels were 12.45 ± 8.62 µU/mL in group 1 and 8.60 ± 5.35 µU/mL in group 2 and 7.04 ± 3.55 µU/mL in group 3 which were statistically significant (P = 0.027). HOMA-IR were 2.92 ± 2.34 in group 1 and 1.95 ± 1.52 in group 2 and 1.60 ± 0.86 in group 3 which were statistically significant (P = 0.046). This study showed that women with PCOS and subclinical hypothyroidism should be evaluated for dyslipidemia and insulin resistance.

Paracrine interactions of thyroid hormones and thyroid stimulation hormone in the female reproductive tract have an impact on female fertility

Thyroid disease often causes menstrual disturbances and infertility problems. Thyroid hormone (TH) acts through its receptors, transcription factors present in most cell types in the body. Thyroid stimulating hormone (TSH) stimulates TH synthesis in the thyroid gland, but seems to have other functions as well in the female reproductive tract. The receptors of both TH and TSH increase in the receptive endometrium, suggesting that they are important for implantation, possible by influencing inflammatory mediators such as leukemia inhibitory factor. The roles of these receptors in the ovary need further studies. However, it is likely that the thyroid system is important for both follicular and embryo development. The association between thyroid disease and infertility indicate that TH and TSH affect the endometrium and ovary on the paracrine level.

Relative associations of polycystic ovarian syndrome vs metabolic syndrome with thyroid function, volume, nodularity and autoimmunity

BACKGROUND

The relative associations of polycystic ovarian syndrome (PCOS) and metabolic syndrome (MS) with the risk for thyroid disease (thyroid function, volume, nodularity and autoimmunity) are unknown.We compared thyroid features and function in patients with PCOS and control subjects by the presence of MS.

METHODS

We recruited 84 women with PCOS and 81 age-matched healthy controls. PCOS was defined according to the Rotterdam criteria. Thyroid ultrasound and function tests were performed in all.

RESULTS

Although thyroid disease was more prevalent in women with PCOS, ovarian disease was not significantly associated with the risk for thyroid disease. Thyroid volume did not differ between women with PCOS and control subjects (13.7±8.6 vs 12.4±4.4 ml, respectively; p=0.2); however, it differed significantly between subjects with and without MS (regardless of PCOS status): 19.1±14.8 vs 12.4±4.9 ml, respectively; p=0.001). Antithyroglobulin and antithyroid peroxidase antibody levels also were significantly higher in subjects with MS, but not in participants with PCOS vs control subjects. Overall, TSH level correlated significantly with body mass index (BMI), weight, waist circumference, diastolic blood pressure, and levels of LDL cholesterol, triglycerides, and HDL cholesterol. Thyroid volume correlated significantly with age, weight, BMI, waist circumference, systolic blood pressure, 120-min postprandial glucose and HDL level.

CONCLUSIONS

PCOS alone was not associated with thyroid disease in our population. However, MS and some of its components appear to be related to thyroid volume, function, and antithyroid antibody levels.

Thyroid hormone receptors and reproduction

Thyroid disorders have a great impact on fertility in both sexes. Hyperthyroidism and hypothyroidism cause changes in sex hormone-binding globulin (SHBG), prolactin, gonadotropin-releasing hormone, and sex steroid serum levels. In females, thyroid hormones may also have a direct effect on oocytes, because it is known that specific binding sites for thyroxin are found on mouse and human oocytes. There is also an association between thyroid dysfunction in women and morbidity and outcome in pregnancy. In males, hyperthyroidism causes a reduction in sperm motility. The numbers of morphologically abnormal sperm are increased by hypothyroidism. When euthyroidism is restored, both abnormalities improve or normalize. In women, the alterations in fertility caused by thyroid disorders are more complex. Hyper- and hypothyroidism are the main thyroid diseases that have an adverse effect on female reproduction and cause menstrual disturbances--mainly hypomenorrhea and polymenorrhea in hyperthyroidism, and oligomenorrhea in hypothyroidism. In recent studies, it has become evident that it is not only changes in serum levels of SHBG and sex steroids that are responsible for these disorders, but also alterations in the metabolic pathway. Adequate levels of circulating thyroid hormones are of primary importance for normal reproductive function. This review presents an overview of the impact of thyroid disorders on reproduction.

Association of subclinical hypothyroidism and phenotype, insulin resistance, and lipid parameters in young women with polycystic ovary syndrome

OBJECTIVE

To determine whether subclinical hypothyroidism (SCH) alters the phenotype, insulin resistance, or lipid parameters in young women with polycystic ovary syndrome (PCOS).

DESIGN

Prospective case-control study.

SETTING

Tertiary care setting.

PATIENT(S)

Sixty-two young women with PCOS and SCH (group I) and 291 euthyroid women with PCOS (group II).

INTERVENTION(S)

Recording of clinical, biochemical, hormonal profile, and parameters of insulin resistance.

MAIN OUTCOME MEASURE(S)

Whether SCH has any association with clinical parameters like hirsutism, menstrual disturbances, lipid profile, and parameters of insulin sensitivity.

RESULT(S)

Mean (±SD) TSH was 7.13±1.28 IU/L in group I and 2.51±1.21 IU/L in group II, with comparable free triiodothyronine and free thyroxine. The two groups were comparable in age, weight, and body mass index. Parameters like blood pressure, menstrual pattern, and degree and duration of hirsutism did not differ between the two groups. Serum concentrations of triglycerides were significantly higher in the SCH group compared with controls. Plasma glucose concentrations both in fasting and after oral glucose tolerance test were similar between the two groups. Fasting insulin and other parameters of insulin resistance were not altered by SCH.

CONCLUSION(S)

Mild TSH elevation in the face of normal serum free triiodothyronine and free thyroxine results in a mild increase in serum lipids. Subclinical hypothyroidism is not associated with alteration in phenotypic expression and insulin resistance in young women with PCOS.

Common genetic variation in the 3'-untranslated region of gonadotropin-releasing hormone receptor regulates gene expression in cella and is associated with thyroid function, insulin secretion as well as insulin sensitivity in polycystic ovary syndrome patients

Gonadotropin-releasing hormone receptor (GNRHR) is a member of the G protein-coupled Ca(2+)-dependent family of receptors. It interacts with GnRH, whose signaling plays an important role in thyroid-stimulating hormone (TSH) secretion and insulin activity. There has been no study on the genetic effect of GNRHR on TSH secretion and insulin action in polycystic ovary syndrome (PCOS). We decided to investigate whether naturally occurring genetic variation at the human GNRHR locus is associated with thyroid function, insulin secretion and insulin sensitivity in PCOS. We undertook a systematic search for polymorphisms in GNRHR by resequencing the gene and then genotyped common single-nucleotide polymorphisms across the locus in 261 PCOS patients well-phenotyped for several metabolic traits to determine associations. A test for association of common genetic variants with susceptibility to PCOS was carried out in a large cohort of 948 subjects. Finally, we experimentally validated the marker-on-trait associations using GNRHR 3'-UTR region/reporter analysis in 293T cells. The 3'-UTR variant rs1038426 was associated with serum thyroid concentration (P = 0.007), change of insulin levels during oral glucose tolerance test (P = 0.004) and insulin sensitivity index (P = 0.014). In a functional study, 3'-UTR variant T allele increased reporter expression by a transfected luciferase reporter/GNRHR 3'-UTR expression plasmid. In conclusion, our results strongly suggest that common genetic variant in GNRHR contributes to the phenotypic expression of PCOS. The findings suggest novel pathophysiological links between the GNRHR locus and thyroid function and insulin secretion in PCOS.

Relationships between thyroid function and lipid status or insulin resistance in a pediatric population

BACKGROUND

In adults without thyroid disease, increasing levels of thyroid-stimulating hormone (TSH) within the range of that considered normal have been shown to be associated with increases in total cholesterol, low-density lipoprotein cholesterol, non-high-density lipoprotein cholesterol, and triglycerides, and with decreases in high-density lipoprotein cholesterol. Serum TSH has also been found to be positively associated with fasting and postload insulin concentrations and negatively associated with insulin sensitivity in euthyroid adults. We hypothesized that such relationships also exist in euthyroid children and adolescents.

METHODS

This was a retrospective record review of pediatric outpatients (ages 2-18 years) having measurements of TSH or free thyroxine (T4) and a concurrent lipid panel, fasting glucose, or fasting insulin. Pearson correlation coefficient was used to estimate the correlation between TSH or free T4 and logarithmic transformed lipid, plasma glucose, or insulin levels. Lipid levels, fasting plasma glucose, insulin, and homeostasis model assessment (HOMA) were also compared between subjects with TSH levels in the high normal range (2.5-5 mIU/L) and those with TSH in the low normal range (0.3-2.4 mIU/L).

RESULTS

TSH levels were positively correlated with triglyceride levels (r = 0.10, p = 0.001). Conversely, free T4 levels were inversely correlated with triglyceride levels (r = -0.10, p = 0.011). TSH levels were also positively correlated with fasting insulin (r = 0.26, p = 0.002) and with HOMA (r = 0.27, p = 0.001). These associations remained significant after adjustment for age, gender, and body mass index z-score. Children who had TSH levels between 2.5 and 5.0 mIU/L had higher triglycerides (p = 0.003), insulin levels (p = 0.040), and HOMA (p = 0.021) than those having TSH values between 0.3 and 2.4 mIU/L.

CONCLUSIONS

In euthyroid children without a history of hypo- or hyperthyroidism, increasing levels of TSH and decreasing levels of free T4 are associated with higher triglyceride levels and elevated markers of insulin resistance. Whether these findings carry implications regarding optimal TSH levels in children at increased risk for cardiovascular disease awaits further study.

The impact of testosterone administration to female-to-male transsexuals on insulin resistance and lipid parameters compared with women with polycystic ovary syndrome

OBJECTIVE

To evaluate the impact of testosterone (T) administration to female-to-male transsexuals (FtMs) on insulin resistance and lipid parameters and to compare the effects with women with polycystic ovary syndrome (PCOS).

DESIGN

Cohort analysis.

SETTING

University hospital.

PATIENT(S)

Twenty-nine FtMs and 240 women with PCOS.

INTERVENTION(S)

Screening panel, ultrasound of the ovaries, hormone, lipid, and glucose and insulin measurements.

MAIN OUTCOME MEASURE(S)

Endocrine, metabolic parameters, and insulin resistance.

RESULT(S)

The PCOS women had significantly higher fasting, 1-h, and 2-h insulin levels and a significantly lower insulin sensitivity index compared with FtMs before and after their T treatment. There were higher triglyceride levels and lower high-density lipoprotein cholesterol levels upon T treatment in FtMs compared with the PCOS women. Women with PCOS had higher body mass index (BMI) values. Positive correlations between insulin resistance indices and BMI were found only in women with PCOS.

CONCLUSION(S)

Testosterone administration by itself showed little detrimental influence on insulin resistance indices, but it had significant effects on lipid profiles. Compared with T, BMI had a greater impact on insulin resistance in women with PCOS.