Question

Parathormone brings about
1) Increase in blood thyroxine level
2) Increase in blood calcium level
3) Decretise in blood thyroxine level
4) Decrease in blood calcium level​

Answer 1

Explanation:

Thyroid disorders and primary hyperparathyroidism have been known to be associated with increases in blood pressure. The hypertension related to hypothyroidism is a result of increased peripheral resistance, changes in renal hemodynamics, hormonal changes and obesity. Treatment of hypothyroidism with levo-thyroxine replacement causes a decrease in blood pressure and an overall decline in cardiovascular risk. High blood pressure has also been noted in patients with subclinical hypothyroidism. Hyperthyroidism, on the other hand, is associated with systolic hypertension resulting from an expansion of the circulating blood volume and increase in stroke volume. Increased serum calcium levels associated with a primary increase in parathyroid hormone levels have been also associated with high blood pressure recordings. The mechanism for this is not clear but the theories include an increase in the activity of the renin–angiotensin–aldosterone system and vasoconstriction. Treatment of primary hyperparathyroidism by surgery results in a decline in blood pressure and a decrease in the plasma renin activity. Finally, this review also looks at more recent evidence linking hypovitaminosis D with cardiovascular risk factors, particularly hypertension, and the postulated mechanisms linking the two.

Keywords: Hypertension, hyperthyroidism, hypothyroidism, primary hyperparathyroidism, vitamin D

Introduction

Thyroid gland along with the parathyroid glands and heart share a close relationship arising in embryology. In ontogeny, the thyroid and heart migrate together. There is a strong physiological relationship between the two organs, which is affirmed by predictable changes in cardiovascular functions across the entire range of thyroid disease states.[1] Many symptoms and signs recognized in patients with overt hyperthyroidism and hypothyroidism are due to increased or reduced action of thyroid hormone on the heart and the vascular system, respectively