Malignant neoplasms in people with hypothyroidism in Spain: A population-based analysis

Comorbidities of hypothyroidism

Hypothyroidism is a relatively common condition that may affect as many as 10% of the population worldwide when its overt and subclinical presentations are considered. Important clinical comorbidities are highly prevalent in people with hypothyroidism and diminish quality of life and functional status in a manner that is proportional to the number of comorbidities present and their severity. This article reviews the common comorbidities of hypothyroidism, as reported in the literature. The comorbidities of hypothyroidism include clinical conditions commonly associated with hypothyroidism, such as dyslipidaemia, hypertension, fatigue or (possibly) cardiovascular disease, and can appear whether or not intervention with LT4 is applied appropriately to ensure biochemical euthyroidism. Other comorbidities may share some pathogenetic background with hypothyroidism, including depression or anxiety, or autoimmune conditions. Hypothyroidism may arise as a comorbidity of some other conditions, e.g. following the application of targeted cancer therapies or some disease-modfying treatments for multiple sclerosis. Other common treatments, including metformin, glucocorticoids or proton pump inhibitors, among others, may alter levels of thyrotropin, thus impacting on the monitoring of thyroid dysfunction and the diagnosis of thyroid dysfunction. Ensuring good control of hypothyroidism is a necessary first step in managing any patient with hypothyroidism. Then, physicians should be aware of the possibility of other comorbid conditions that must be addressed to achieve an optimal patient outcome.

Navigating the thyroid-gynecologic interplay: a systematic review and meta-analysis

Thyroid disorders are considered to be linked to various health issues, including gynecologic cancers. Studying this association is crucial in clinical practice. This approach was applied through searches in Scopus, WOS, PubMed, and Google Scholar. A Preferred Reporting Items for Systematic Reviews and Meta-Analyses checklist was followed. The quality assessment was checked. The meta-analyses were performed using R-4.3.2 (R Core Team, Vienna, Austria) and SPSS version 28 (SPSS Inc., Armonk, NY, USA). The results demonstrated that 19 studies investigated the association between thyroid disorders and gynecologic cancers in adult females. The studies were categorized into two groups: group 1 examined thyroid status in various gynecologic cancers, while group 2 comprised casecontrol studies examining gynecologic cancer incidence in females with thyroid disorders compared to control. Among females with gynecologic cancers, 13% (95% confidence interval [CI], 10-17%) had hypothyroidism. When comparing hypothyroidism and hyperthyroidism across studies, the overall percentage for hypothyroidism was 14% (95% CI, 9-22%), while for hyperthyroidism, it was 3% (95% CI, 2-5%). The odds ratio for hypothyroidism in females with uterine cancer was 2.65 (P<0.05). Additionally, hypothyroidism showed a significant risk ratio of 1.3 (P<0.05) for different gynecologic cancers. However, hyperthyroidism was significantly associated with increased ovarian cancer mortality (risk ratio [RR], 2.14; P=0.03); conversely, hypothyroidism showed no significant relationship (RR, 1.35; P=0.26). The findings concluded that hypothyroidism is significantly associated with various gynecologic cancers, suggesting a potential role in its pathogenesis. Conversely, hyperthyroidism is linked to an increased risk of ovarian cancer mortality. Further research is needed to clarify whether hyperthyroidism predisposes females to ovarian cancer.

Causal relationship between thyroid dysfunction and gastric cancer: a two-sample Mendelian randomization study

Backgroud

Gastric cancer is one of the most common cancers worldwide, and its development is associated with a variety of factors. Previous observational studies have reported that thyroid dysfunction is associated with the development of gastric cancer. However, the exact relationship between the two is currently unclear. We used a two-sample Mendelian randomization (MR) study to reveal the causal relationship between thyroid dysfunction and gastric cancer for future clinical work.

Materials and methods

This study is based on a two-sample Mendelian randomization design, and all data are from public GWAS databases. We selected hyperthyroidism, hypothyroidism, free thyroxine (FT4), and thyroid-stimulating hormone (TSH) as exposures, with gastric cancer as the outcome. We used three statistical methods, namely Inverse-variance weighted (IVW), MR-Egger, and weighted median, to assess the causal relationship between thyroid dysfunction and gastric cancer. The Cochran's Q test was used to assess the heterogeneity among SNPs in the IVW analysis results, and MR-PRESSO was employed to identify and remove IVs with heterogeneity from the analysis results. MR-Egger is a weighted linear regression model, and the magnitude of its intercept can be used to assess the horizontal pleiotropy among IVs. Finally, the data were visualized through the leave-one-out sensitivity test to evaluate the influence of individual SNPs on the overall causal effect. Funnel plots were used to assess the symmetry of the selected SNPs, forest plots were used to evaluate the confidence and heterogeneity of the incidental estimates, and scatter plots were used to assess the exposure-outcome relationship. All results were expressed as odds ratios (OR) and 95% confidence intervals (95% CI). P<0.05 represents statistical significance.

Results

According to IVW analysis, there was a causal relationship between hypothyroidism and gastric cancer, and hypothyroidism could reduce the risk of gastric cancer (OR=0.936 (95% CI:0.893-0.980), P=0.006).This means that having hypothyroidism is a protective factor against stomach cancer. This finding suggests that hypothyroidism may be associated with a reduced risk of gastric cancer.Meanwhile, there was no causal relationship between hyperthyroidism, FT4, and TSH and gastric cancer.

Conclusions

In this study, we found a causal relationship between hypothyroidism and gastric cancer with the help of a two-sample Mendelian randomisation study, and hypothyroidism may be associated with a reduced risk of gastric cancer, however, the exact mechanism is still unclear. This finding provides a new idea for the study of the etiology and pathogenesis of gastric cancer, and our results need to be further confirmed by more basic experiments in the future.

Thyroid dysfunction and risk of cutaneous malignant melanoma: a bidirectional two-sample Mendelian randomization study

Background

Epidemiologic and observational data have found a risk association between thyroid dysfunction and cutaneous malignant melanoma (CMM), however, the cause and direction of these effects are yet unknown. By using a bidirectional two-sample Mendelian randomization (MR) methodology, we hoped to further investigate the causal link between thyroid dysfunction and CMM in this work.

Methods

A genome-wide association study (GWAS) of 9,851,867 single nucleotide polymorphisms (SNPs) in a European population was used to develop genetic tools for thyroid dysfunction. Hypothyroidism was linked to 22,687 cases and 440,246 controls. For hyperthyroidism, there were 3545 cases and 459,388 controls. A total of 3751 cases and 372016 controls were included in the genetic data for CMM from UK Biobank (http://www.nealelab.is/uk-biobank) (the Dataset: ieu - b - 4969). Among them, inverse variance weighting (IVW) is the main MR Analysis method for causality assessment. MR-Egger method, MR Pleiotropic residual and outlier test (MR-PRESSO), and simple and weighted median (VM) were used to supplement the IVW method. Sensitivity analyses, mainly Cochran's Q test, leave-one-out analysis, and MR Egger intercept test were performed to assess the robustness of the outcomes.

Results

The two-sample MR Analysis results revealed a negative correlation between genetically predicted hypothyroidism and the probability of CMM (OR=0.987, 95%CI =0.075-0.999, p=0.041). The supplemental MR Analysis did not reveal any statistically significant differences, although the direction of the effect sizes for the other approaches was consistent with the IVW effect sizes. The results of the causal analysis were relatively robust, according to a sensitivity analysis. The risk of CMM was unaffected by hyperthyroidism (p>0.05). No correlation between CMM and thyroid dysfunction was seen in the reverse MR analysis.

Conclusion

Although the magnitude of the causal association is weak and further investigation of the mechanism of this putative causal relationship is required, our findings imply that hypothyroidism may be a protective factor for CMM.

Prevalence of thyroid dysfunction and its relationship to income level and employment status: a nationwide population-based study in Spain

PURPOSE

The influence of socioeconomic conditions on the prevalence of thyroid dysfunction in the population has been scarcely studied to date. The aim of this study has been to evaluate the influence of income level and employment status on the prevalence of hypothyroidism and hyperthyroidism.

METHODS

A cross-sectional study was performed using the population-based database BDCAP (Base de Datos Clínicos de Atención Primaria, Primary Care Clinical Database) to analyze the prevalence of thyroid dysfunction in the Spanish population classified by income groups and employment status.

RESULTS

Of the 40,613,229 people registered in the BDCAP in 2020, there were 2,596,041 (6.39%) with a diagnosis of hypothyroidism and 418,722 (1.03%) with hyperthyroidism. The prevalence of hypothyroidism in people with high income (≥ 100,000 euros/year), medium income (18,000-99,999 euros/year), low income (< 18,000 euros/year), and very low income were, respectively, 4.23%, 5.74%, 6.75%, and 7.01% (P < 0.001). The prevalence of hyperthyroidism in the same income groups also showed an increasing trend as income decreased (0.65%, 0.94%, 1.08%, and 1.10%; P < 0.001). Unemployed people had higher frequencies of hypothyroidism (7.35%) and hyperthyroidism (1.22%) than working people (5.80 and 1.00%, respectively) and inactive people (4.21 and 0.52%, respectively; P < 0.001).

CONCLUSION

Socioeconomic conditions are related to the prevalence of thyroid dysfunction. Low-income or unemployed people have a higher frequency of both hypothyroidism and hyperthyroidism.