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

Prevalence of subclinical hypothyroidism in polycystic ovary syndrome and its impact on insulin resistance: a systematic review and meta-analysis

BACKGROUND

Although recent studies indicate a high prevalence of subclinical hypothyroidism (SCH) in women with polycystic ovary syndrome (PCOS), the reported prevalence rates vary widely. Therefore, we conducted this study to estimate the pooled prevalence of SCH among women with PCOS. Additionally, emerging evidence suggests that SCH may negatively impact insulin resistance in PCOS. Thus, we examined its effect on insulin resistance indices as our secondary objective.

METHODS

We searched PubMed, Web of Science, Scopus, and Embase from their inception to February 25, 2024. Observational studies reporting the prevalence of SCH among women with PCOS were included. Joanna Briggs Institute's (JBI) critical appraisal checklist for prevalence studies was adopted for the risk of bias assessment. The random-effects model was employed to estimate the pooled prevalence with its 95% confidence intervals (CI). The weighted mean difference (WMD) was used to compare the insulin resistance indices between PCOS patients with and without SCH.

RESULTS

Twenty-nine studies comprising 5765 women with PCOS were included. The meta-analysis demonstrated that 19.7% (95% CI: 16.1%; 23.5%) of women with PCOS have SCH. PCOS patients with SCH had significantly higher HOMA-IR (WMD = 0.78, 95% CI: 0.34; 1.22) and fasting insulin (WMD = 2.38, 95% CI: 0.34; 4.42) levels than those without SCH. Differences in fasting plasma glucose and 2-hour postprandial glucose did not reach statistical significance.

CONCLUSION

This systematic review and meta-analysis found that approximately 20% of women with PCOS have SCH. This underscores the need for regular thyroid function testing in these patients. The prevalence of SCH is influenced by the TSH cut-off used for diagnosis, highlighting the need for establishing a standardized TSH cut-off value. Furthermore, SCH significantly elevates the HOMA-IR index and fasting insulin levels, highlighting its potential impact on insulin resistance. Whether these metabolic changes are clinically important and put these individuals at higher risk of developing type 2 diabetes mellitus and cardiovascular disease requires further investigation.

SYSTEMATIC REVIEW REGISTRATION NUMBER IN PROSPERO

CRD42024510798.

CLINICAL TRIAL NUMBER

Not applicable.

Endometriosis, polycystic ovary syndrome, and the thyroid: a review

Endometriosis and polycystic ovary syndrome (PCOS) are common gynecological disorders that constitute a significant burden of disease in women of fertile age. The disorders share a link to female reproduction and infertility; however, divergent effects on menstrual cycle, related hormones, and body composition have been proposed. Disorders of the thyroid gland including abnormal thyroid dysfunction (hyperthyroidism or hypothyroidism) and/or markers of thyroid autoimmunity similarly show a female predominance and onset in younger age groups. We reviewed the literature on the association between endometriosis, PCOS, and thyroid disease up until July 1, 2023, and identified 8 original studies on endometriosis and thyroid disease and 30 original studies on PCOS and thyroid disease. The studies were observational and heterogeneous regarding the design, sample size, and definitions of exposure and outcome; however, a tendency was seen toward an association between hyperthyroidism and endometriosis. Especially an association between endometriosis and slightly elevated levels of thyroid-stimulating hormone receptor antibodies has been found and corroborated in studies from different populations. On the other hand, the literature review turned a focus toward an association between hypothyroidism and PCOS, however, with uncertainties as to whether the association is caused by hypothyroidism per se and/or the thyroid autoantibodies (thyroid peroxidase and thyroglobulin antibodies). More evidence is needed to substantiate an association between endometriosis, PCOS, and thyroid disease, and to differentiate between the role of thyroid function and thyroid autoimmunity. Furthermore, studies are warranted to extend knowledge on the different disease characteristics and underlying mechanisms.

Assessment of Metabolic Parameters in Female Triathletes with Hashimoto’s Thyroiditis in Poland

Background: Hypothyroidism is a complex disorder characterized by an increase in body weight. About 15–30% of hypothyroid patients are reported to be overweight. The triathlon is an endurance combination sport that comprises a sequential swim, cycle, and run. Triathletes must withstand high training loads with various combinations of intensity and volume. Adequate body structure, the ratio of fat and muscle tissue, and adequate hydration play a huge role. The aim of our study was to show the potential differences in metabolic parameters assessed by medical Body Composition Analyzer before the initiation of treatment with L-thyroxine and after 3 and 6 months of treatment in females who practiced triathlon and who were newly diagnosed with Hashimoto’s thyroiditis. Methods: The study group included 32 females practicing triathlon. They were recruited for 10 months from March to December 2021. Analysis of anthropometric measurements was performed using a seca device mBCA 515 medical Body Composition Analyzer. Results: We observed significant differences in FM and VAT before and after L-thyroxine treatment. We also noticed lower BMI levels after treatment, along with significant differences in thyroid function tests (TSH and fT4) carried out during the recruitment period and after 3 and 6 months of treatment. Conclusion: Due to their higher daily energy consumption, further research is needed into the treatment of Hashimoto’s thyroiditis in athletes who practice triathlon. Frequent bioelectrical impedance analysis of body composition during treatment can be very helpful.

Correlation between Hashimoto's thyroiditis and polycystic ovary syndrome: A systematic review and meta-analysis

OBJECTIVE

A growing body of research suggests that patients with polycystic ovary syndrome (PCOS) may be at increased risk of developing Hashimoto's thyroiditis (HT), and having both conditions can make the condition worse. However, current research views are not uniform. Therefore, to explore the link between PCOS and HT, we conducted this study.

METHODS

From the establishment of the database to August 2022, we searched 2 databases to study the correlation between Hashimoto's and polycystic ovary syndrome. Two authors independently screened the articles for eligibility, and three authors extracted relevant data. Statistical analysis was performed using STATA16.0 software.

RESULTS

A total of 20 studies were included, including 7 case-control studies and 13 cross-sectional studies. A total of 13 countries and 7857 participants were embraced. Studies have demonstrated that both PCOS patients have an increased risk of HT, and meanwhile, HT patients also have an increased risk of PCOS compared with controls. The study also incorporated that the prevalence of HT in PCOS patients in India and Turkey was higher than in other countries, and the prevalence of HT in PCOS patients in South America was higher than in Asia and Europe.

CONCLUSIONS

In conclusion, our study illustrates that there is a correlation between PCOS and HT, and it is necessary to further study the underlying mechanism between PCOS and HT. At the same time, it is of great significance to regularly screen PCOS patients for HT risk and HT patients for PCOS risk.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/prospero/, identifier CRD 42022351168.

Is there a Relationship between Serum IGF-1 and Thyroid Nodule, Thyroid or Ovarian Volume in Polycystic Ovarian Syndrome?

Context

Studies investigating the association between serum IGF-1, and thyroid nodule, ovarian or thyroid volume in polycystic ovarian syndrome (PCOS) are limited.

Objective

We aimed to analyze the association between serum IGF-1 level, and ovarian or thyroid volume, or thyroid nodule in PCOS.

Design

The study was performed between June 2017 and August 2019 as prospective design.

Subjects and Methods

Adult females with new-onset PCOS were included. The patients having comorbid illness, or using medication were excluded. Basic tests, thyroid and ovarian sonography were performed. The patients were grouped according to thyroid nodule(absent/present) and ovarian volume (<10mL/≥10mL). We planned to find a positive association between IGF-1, and thyroid nodule, thyroid or ovarian volume in PCOS.

Results

Of total 118 patients, 11(9%) had thyroid nodule. The patients with thyroid nodule had a higher ovarian volume (p=0.006). No correlation was found between GH or IGF-1, and thyroid or ovarian volume. IGF-1 was not a predictor for thyroid nodule or higher ovarian volume. Thyroid nodule was a significant predictor for higher ovarian volume.

Conclusion

Our study is the first to analyze the association between IGF-1 and thyroid nodule in PCOS. We found that thyroid nodule was associated with thyroid and ovarian volume, but IGF-1 was not associated with thyroid nodule, thyroid or ovarian volume.

Birth control pills and risk of hypothyroidism: a cross-sectional study of the National Health and Nutrition Examination Survey, 2007-2012

OBJECTIVE

The association between use of birth control pills and thyroid function in women has not ever been well studied, but potential risk has been implicated by small sample-sized studies. We aimed to determine this association using a large epidemiological survey.

DESIGN

Cross-sectional study.

SETTING

National Health and Nutrition Examination Survey conducted in the USA from 2007 to 2012.

PARTICIPANTS

Female respondents aged 18+ who had data on history of taking birth control pills and thyroid function were included. History of taking birth control pills was based on responses on the reproductive health questionnaire. Participants not on antithyroid medication with thyroid-stimulating hormone (TSH) >5.6 mIU/L and those on thyroid hormone replacement regardless of TSH were categorised as hypothyroid. Participants not on thyroid hormone replacement or antithyroid medication who had TSH between 0.34 mIU/L and 5.6 mIU/L were classified as euthyroid.

PRIMARY AND SECONDARY OUTCOME MEASURES

Association between use of birth control pills and hypothyroidism based on multivariate logistic regression analysis.

RESULTS

A total of 5116 female adults with history of taking birth control pills (n=3034) and without (n=2082) were included. A higher prevalence of hypothyroidism was found in those who have ever taken birth control pills (17.7% vs 14.1%; p=0.003). Multivariate logistic regression adjusted for confounding covariables, including age, race, education, body mass index, smoking status, alcohol use, history of thyroid disease, current thyroid disease, first menstrual age, pregnancy history, menopause status and history of hormone replacement use, demonstrated a significant association between history of taking birth control pills for more than 10 years and hypothyroidism (OR, 3.837; 95% CI 1.402 to 10.500; p=0.009).

CONCLUSIONS

Longer history of using birth control pills was strongly associated with hypothyroidism, especially for more than 10 years.

Impact of Subclinical Hypothyroidism on Reproductive and Metabolic Parameters in Polycystic Ovary Syndrome - A Cross-sectional Study from Bangladesh

INTRODUCTION

Separately, polycystic ovary syndrome (PCOS) and subclinical hypothyroidism (SCH) exert adverse effects on several reproductive and metabolic parameters; however, in conjunction, their effects are unclear. This study evaluated the impact of SCH on reproductive and metabolic parameters in women with PCOS.

METHODS

In this cross-sectional study, women with newly diagnosed PCOS were evaluated. Data on their clinical presentation and anthropometric measurements were recorded, in addition to oral glucose tolerance test, fasting lipid profile, serum thyroid-stimulating hormone (TSH), free thyroxine (FT4) and anti-thyroid peroxidase (anti-TPO).

RESULTS

Four hundred and sixty-five women, aged 12-40 years, with PCOS were included in this study; 10.8% of them had SCH and 18.3% were positive for anti-TPO. All participants had statistically similar mean age, body mass index (BMI), waist circumference, systolic blood pressure (BP) and diastolic BP. A similar number of participants in both the euthyroid PCOS and PCOS-SCH groups had menstrual irregularity, acne, subfertility, a first-degree family member with thyroid dysfunction, acanthosis nigricans and elevated BP. Participants with SCH-PCOS had a lower modified Ferriman-Gallwey score and hirsutism frequency, though serum total testosterone levels were similar in the two groups. More subjects in the SCH group were overweight/obese, and had central obesity and goiter compared to the euthyroid group. Blood glucose, lipids and prolactin levels were similar between the two groups; the frequencies of dysglycaemia and dyslipidaemia were also similar. A higher frequency of metabolic syndrome was observed in the SCH group, though the difference was not statistically significant (p=0.098).

CONCLUSION

In women with PCOS, the presence of SCH does not amplify the risk of metabolic and reproductive dysfunctions.