Table 3.
Main clinical studies on potential correlations between thyroid disease and PCOS.
| References | Country | Study design | Patients studied (n.) | Aim | Conclusions |
|---|---|---|---|---|---|
| AIT and PCOS | |||||
| Du and Li, (14) | China | Meta-analysis | 1605 (726 PCOS patients vs 879 patients without PCOS) | To assess the relationship between PCOS and thyroiditis | Prevalence of AIT in patients with PCOS is significantly higher than in patients without PCOS. Data suggest that PCOS may be associated with AIT |
| Romitti et al., (15) | Brazil | Meta-analysis | 2197 (1210 PCOS patients vs 987 patients without PCOS) | To estimate AIT prevalence and risk in women with PCOS | Meta-analysis provides evidence of higher AIT prevalence in patients with PCOS compared with healthy patients. Physicians should consider screening for thyroid function and thyroid-specific autoantibodies at PCOS diagnosis, even in the absence of symptoms related with thyroid dysfunction |
| Ho et al., (16) | China | Cohort | 33655 (cases: 6731 women with AIT (5399 GD and 1332 HT); 26924 healthy women | To investigate PCOS prevalence and its comorbidities in patients with AIT | Findings support the established common mechanism between PCOS and AIT |
| Kim et al. (17) | Korea | Case-control | 553 (210 PCOS patients vs 343 healthy women) | To assess the prevalence of anti-TPO Ab and hypoechoic USG in women with PCOS | AIT is not more prevalent in women with PCOS vs women without PCOS. However, among women with PCOS, patients with AIT have a significantly higher adiposity and insulin resistance index vs those without AIT |
| SCH and PCOS | |||||
| Ding et al., (18) | China | Meta-analysis | 1232 (692 patients with PCOS vs 540 patients without PCOS) | To evaluate SCH prevalence in women with PCOS | SCH risk is higher in women with PCOS vs women without PCOS |
| Zhang et al., (19) | China | Cohort | 34 obese patients with SHC vs obese patients without SCH | To determine whether SCH increases prevalence of PCOS | PCOS frequency does not differ between the two groups (56.1% for normal thyroid function vs 60.2% for SCH) |
| Kamrul-Hasan et al., (20) | Bangladesh | Case-control | 465 (50 PCOS patients vs 415 patients without PCOS) | To assess if SCH in women with PCOS is a metabolic/reproductive risk factor | The similar adverse reproductive and metabolic consequences in women with PCOS with/without SCH indicates that these consequences are due to PCOS alone; the additional presence of SCH in these patients may not impart additional risks |
| Raj et al., (21) | Pakistan | Case-control | 400 (200 patients with PCOS vs 200 patients without PCOS) | To assess if SCH is more frequent in women with PCOS vs healthy women | Data suggest a strong association of SCH in women with PCOS vs healthy women |
| Xu et al. (19) | China | Cohort | 3189 (594 patients with PCOS vs 2595 patients without PCOS) | To evaluate the effect of TSH on IVF outcomes | TSH level in patients with PCOS with normal thyroid function is higher than that in patients without PCOS, and is negatively correlated with the oocyte maturation in IVF |
| Gawron et al., (22) | Poland | Cohort | 367 women with PCOS | To evaluate whether SCH with/without anti-thyroid Ab impacts on the PCOS phenotype and alters biochemical/clinical parameters | SCH alters metabolic, but not hormonal, parameters in PCOS. Among all parameters studied, the strongest relationship with SCH is confirmed for insulin resistance and dyslipidaemia. |
| Rojhani et al., (23) | Iran | 851 (207 PCOS patients vs 644 patients without PCOS) | To assess whether there is a difference between PCOS and control groups in terms of the upper reference limit of TSH and to identify SCH prevalence in women with PCOS vs women without PCOS | SCH prevalence and the upper reference limit of TSH are not significantly different in patients with PCOS vs patients without PCOS | |
| GD and PCOS | |||||
| Glintborg et al., (24) | Denmark | Cohort | 73223 (18476 patients with PCOS vs 54757 healthy women) | To investigate risk of thyroid disease in Danish women with PCOS | Findings highlight the importance of screening for thyroid disease at the time of PCOS diagnosis and during patient follow-up |
| Chen et al., (25) | Taiwan | Cohort | 16197 (5399 women with GD vs 10798 women without GD) | To assess whether GD is a risk factor for developing PCOS | Women with GD are at a risk of developing PCOS. A higher incidence of comorbidities, including hyperlipidaemia, is noted in women with GD and PCOS |
| Botello et al., (26) | Colombia | Meta-analysis | 47509 patients with thyroid autoimmunity | To determine the prevalence of these types of polyautoimmunity in patients with AIT as the index condition | Latent and overt polyautoimmunity are common in patients with AIT |
| Goiter/thyroid nodules and PCOS | |||||
| Duran et al., (27) | Turkey | Case-control | 133 (70 PCOS patients vs 60 healthy women) | Estimate the frequency of nodular goiter in patients with PCOS | It is not possible to demonstrate a significant relation between thyroid volume, thyroid nodule, and AIT frequency in patients with/without PCOS. The increased frequency of goiter and AIT in patients with PCOS may be related to a component of metabolic syndrome rather than the PCOS diagnosis |
| Glintborg et al., (24) | Denmark | Cohort | 18476 (1146 PCOS patients vs 54757 women without PCOS) | To investigate risk of thyroid disease in Danish women with PCOS | Data demonstrate a risk of developing a goiter that is significantly higher in women with PCOS vs healthy controls |
AIT, autoimmune thyroid disease; anti-TPO Ab, anti-thyroid peroxidase antibody; CI, confidence interval; GD, Graves’ disease; HT, hypothyroidism; IVF, in vitro fertilization; OR, odds ratio; PCOS, polycystic ovary syndrome; SCH, subclinical hypothyroidism; TSH, thyroid stimulating hormone; USG, ultrasonography.