The Influence of Treated and Untreated Subclinical Hypothyroidism on Metabolic Profile in Women with 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.

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.

Effect of Oral Chinese Herbal Preparations Regulating Intestinal Flora on Lipid Metabolism Disorders in Patients: A Meta-Analysis of Controlled Clinical Studies

Background

Lipid metabolism disorders can damage human health, and the changes in human intestinal flora are closely related to lipid metabolism disorders. Traditional Chinese medicine (TCM) can play a role in regulating intestinal flora and balancing intestinal microecology. In this meta-analysis, the role of oral preparations of TCM that regulate intestinal flora, in the prevention and treatment of lipid metabolism disorders, was systematically evaluated.

Methods

The databases CBM, Pubmed, Embase, CNKI, Wanfang, and Google Scholar were searched by rapid matching of keywords to obtain clinical controlled studies related to oral preparations of TCMs regulating intestinal flora. After screening and quality evaluation, meta-analysis was performed using Review Manager 5.3 software.

Results

Total of 835 patients were enrolled in the 10 articles included in this study. Meta-analysis showed that TCM intervention could reduce the level of total cholesterol (TC) in patients with abnormal lipid metabolism [mean difference (MD) = −0.61, 95% confidence interval (95%CI) (−0.80, −0.42), p < 0.00001], reduce triacylglycerol (TG) level [MD = −0.46, 95%CI (−0.60, −0.33), p < 0.00001], increase high-density lipoprotein (HDL) level [MD = 0.25, 95%CI (0.17, 0.34), p < 0.00001], reduce the number of intestinal enterobacteria [MD = −0.64, 95%CI (−0.79, −0.49), p < 0.00001], reduce the number of enterococci [MD = −1.14, 95%CI (−1.66, −0.63), p < 0.00001], increase the number of intestinal lactobacillus [MD = 0.41, 95%CI (0.09, 0.74), p = 0.01], and increase the number of intestinal bifidobacteria [MD = 0.94, 95%CI (0.20, 1.68), p = 0.01].

Conclusion

The application of oral preparations of TCMs that regulate intestinal flora, in the prevention and treatment of lipid metabolism disorders, can increase the colonization of beneficial bacteria in the intestine of patients, inhibit the growth of harmful bacteria, and restore the intestinal microecological balance, thus indirectly acting on the regulation of blood lipids in patients and contributing to the recovery of dyslipidemia.

Two MMP2 gene polymorphisms significantly associated with polycystic ovary syndrome: A case-control analysis

PURPOSE

To study the association between MMP2 gene polymorphisms (rs7201 and rs243849) and polycystic ovary syndrome (PCOS) risk.

METHODS

1287 participants, including 592 PCOS and 623 controls, were collected. In analysis, six genotype models (dominant model: MM + MW vs. WW; recessive model: MM vs. MW + WW; over-dominant model: MM + WW vs. MW; co-dominant model: MM vs. MW; co-dominant model: MM vs. WW; allele analysis: M vs. W, where M: minor allele; W: major allele) were applied. Subgroup analyses were performed based on race and obesity.

RESULTS

In the whole sample, only rs7201 was identified to protect from the PCOS (unadjusted: Recessive MM vs MW + WW, OR = 0.551, 95%CI = 0.311-0.974, P = 0.040; co-dominant MM vs WW, OR = 0.541, 95%CI = 0.304-0.964, P = 0.037). Subgroup analysis also identified rs243849 to be significantly associated with PCOS risk in the Han race (unadjusted: co-dominant MM vs WW, OR = 0.383, 95%CI = 0.153-0.961, P = 0.041; Allele M vs W, OR = 0.729, 95%CI = 0.553-0.963, P = 0.026). Moreover, rs243849 could regulate prominently MMP2 gene expression. However, no statistical significances were identified in the obesity groups (body mass Index and waist-hip ratio).

CONCLUSIONS

We identified for the first time that both rs7201 and rs243849 of MMP2 could protect from PCOS. Further studies with larger samples are needed to confirm the conclusion.