Thyroid physiology

Question 1

What are the negative feedback circuits that control TSH release?

Answer 1

Requires T3, which is formed in the anterior pituitary from T4

Question 2

What is the cause of Grave’s disease? What are the effects?

Answer 2

Autoantibodies bind to and stimulate TSH receptors, leading to excessive amounts of thyroid hormone

Question 3

What is the cause of Hashimoto disease? What are the effects?

Answer 3

Autoantibodies directed against thyroglobulin or thyroid peroxidase, resulting in low TH production (and high circulating TSH) and eventual destruction of the thyroid gland

Question 4

What is the major thyroid hormone binding protein in the blood?

Answer 4

Thyroxine binding globulin (TBG)

Question 5

What is iodide trapping?

Answer 5

Concentrating iodide in the thyroid epithelial cell

Question 6

What is organification?

Answer 6

Binding iodine with thyroglobulin in the follicular lumen

Question 7

What is the role of thyroxine binding prealbumin?

Answer 7

Transthyretin - can transport thyroid hormone and retinol

Question 8

Which thyroid binding protein is semi-specific for circulating thyroid hormones?

Answer 8

Transthyretin