Thyroid Hormone Resistance Syndrome: From Molecular Mechanisms to Its Potential Contribution to Hypertension.

Thyroid hormone resistance (THR) is a rare inherited disorder that affects approximately one in every 40,000 live births. This condition arises from a mutation in the thyroid hormone receptor β, leading to reduced responsiveness of target tissues. It can result in a combination of hypothyroidism and hyperthyroidism symptoms in different tissues. The thyroid hormone is crucial for controlling blood pressure, and even small changes in its levels can have an effect on vascular resistance, cardiac performance, and heart rhythm. Both hypo- and hyperthyroidism have been associated with elevated blood pressure, underscoring the significant link between thyroid hormone sensitivity and vascular function. Considering thyroid hormone sensitivity is essential in clinical practice, particularly when managing patients with hypertension, to ensure personalized and effective treatment approaches. Monitoring thyroid function is essential during the diagnosis of hypertension, as thyroid dysfunction can often be corrected to normalize blood pressure. It's crucial to distinguish between essential hypertension and hypertension associated with a thyroid abnormality in THR. The mechanisms behind the development of hypertension in THR include reduced nitric oxide production, dysregulation of the renin-angiotensin-aldosterone system, impaired endothelial function, and mutations in the deiodinases. Physicians should understand the underlying mechanisms of THR and identify new therapeutic targets for hypertension in THR.