CLINICAL IMPLICATIONS OF THYROID HORMONE IMBALANCES IN THE DEVELOPMENT OF CARDIOMETABOLIC DISORDERS

Abstract

Thyroid hormones are key regulators of cardiovascular activity and whole-body metabolism, but the exact extent, form and mechanistic basis of relationships among thyroid malfunction and cardiometabolic phenotype remain not fully delineated. The present review summarizes the existing evidence to outline the complicated relationship between thyroid hormone imbalances and the pathogenesis of cardiometabolic diseases. Systematic review and meta-analysis were done of 47 prospective cohort studies (47 studies) and 1,284,376 participants to determine relationships between thyroid-stimulating hormone, free triiodothyronine, free thyroxine and the incidence of cardiovascular events, dyslipidemia, hypertension and insulin resistance. Random-effects models were used to synthesize the effect estimates, non-linear dose-response relationships were modeled using cubic splines and significant modifiers of effects were identified using meta-regression. Overt hyperthyroidism had the greatest risk of atrial fibrillation with a hazard ratio of 2.14 and overt hypothyroidism exhibited the greatest risk of heart failure and the most atherogenic lipid profile, raising LDL-cholesterol by 0.89 millimoles per liter and triglycerides by 0.48 millimoles per liter. The relationship between thyroid-stimulating hormone and cardiovascular events exhibited a unique U-shaped pattern where the risk peak was found in the range of 1.0 to 2.0 milli-international units per liter of thyroid-stimulating hormone and which increased in risk at both ends. Increased negatively related to cardiovascular events and insulin resistance. Body mass index and diabetes emerged as positive effect modifiers with significant values in meta-regression, and point to a synergistic effect of cardiovascular risk in the case of thyroid dysfunction in the presence of metabolic comorbidities. Subclinical and overt cases of thyroid dysfunction are non-linearly, hormone-dependent predictors of adverse cardiometabolic outcomes. The encouraging biomarker of peripheral thyroid hormone activity, and metabolic comorbidities are great amplifiers of cardiovascular risk. These results endorse the incorporation of thyroid functional evaluation into cardiovascular risk stratification models and indicate that the cardiometabolic burden of thyroid conditions could be mitigated with the aid of specific management of the modifiable risk factors.