Thyroid hormone and blood pressure regulation

Abstract

Thyroid hormone has well-recognized effects on the cardiovascular system and blood pressure regulation. Blood pressure is altered across the entire spectrum of thyroid disease. The effects of hyperthyroidism include increased cardiac output, contractility, tachycardia, widened pulse pressure, decreased systemic vascular resistance, and increased basal metabolic rate. The manifestations of hypothyroidism are in marked contrast to those of hyperthyroidism and include decreased cardiac output, narrow pulse pressure, increased systemic vascular resistance, and decreased metabolic rate. Although thyroid hormone affects almost all tissues of the body and mediates changes in homeostasis, adaptations of the cardiovascular system can result in changes in blood pressure to accommodate the new demands on the system. In this paper, we review the direct and indirect thyroid hormone-mediated effects on blood pressure.

Thyroid Disease and the Heart

“…55,56 Thyroid hormone increases basal metabolic rate in almost every tissue and organ system in the body, and the increased metabolic demands lead to changes in cardiac output, SVR, and blood pressure ( Figure 2). 54 In many regards these changes are similar to the physiological response to exercise. 54,57 A widened pulse pressure is characteristic of hyperthyroidism.…”

“…54 In many regards these changes are similar to the physiological response to exercise. 54,57 A widened pulse pressure is characteristic of hyperthyroidism. Recent reports have shown that arterial stiffness is increased in hyperthyroidism despite the low SVR.…”

“…53, 54 Asvold et al 53 report a linear correlation between TSH and both systolic and diastolic blood pressure, whereas other studies do not find a correlation. 55,56 Thyroid hormone increases basal metabolic rate in almost every tissue and organ system in the body, and the increased metabolic demands lead to changes in cardiac output, SVR, and blood pressure ( Figure 2).…”

“…It has been suggested that the effect of thyroid hormone to decrease SVR may not occur in the pulmonary vasculature. 54 Both pulmonary hypertension and atrioventricular valve regurgitation have been documented to occur with a surprisingly high prevalence. 59,60 Several case reports have documented that hyperthyroidism may present as right heart failure and tricuspid regurgitation.…”

“…60 It may be that some component of the "right heart failure" and peripheral edema that can accompany hyperthyroidism is caused by this reversible change in pulmonary artery pressure. 54,61 Primary pulmonary hypertension is a progressive disease that leads to right heart failure and premature death and is often of unknown origin. It is most common in young women, and it is defined by a pulmonary artery pressure Ͼ25 mm Hg at rest and Ͼ30 mm Hg during exercise.…”