Bishop Chapter 23 The Thyroid Gland

Question 1

The thyroid gland is responsible for the production of what two hormones?

Answer 1

Thyroid hormone and calcitonin.

Question 2

What is the clinical significance of calcitonin?

Answer 2

Secreted by parafollicular C cells and is involved in calcium hemostasis.

Question 3

The parathyroid glands regulates ___.

Answer 3

Serum calcium levels.

Question 4

Define hypothyroidism.

Answer 4

The thyroid doesn’t create and release enough thyroid hormone.

Question 5

Why is the thyroid hormone critical for fetuses?

Answer 5

Can cause fetal neurologic development and hypothyroidism can lead to mental retardation (or cretinism).

Question 6

Thyroid hormone is made primarily of what trace element?

Answer 6

Iodine.

Question 7

Thyroid cells are organized into spheres surrounding a central core of fluid called what?

Answer 7

Colloid.

Question 8

What is the major component of colloid?

Answer 8

Thyroglobulin.

Question 9

What are the two active forms of thyroid hormone?

Answer 9

Triiodothyronine (T3) and Thyroxine (T4).

Question 10

What is the clinical significance of the thyroid stimulating hormone (TSH)?

Answer 10

Stimulates the production of two main hormones, T4 and T3.

Question 11

Which thyroid hormone is more metabolically active?

Answer 11

T3 which is 3 to 8 times more active than T4.

Question 12

What are the three major binding proteins, in order of significance?

Answer 12

Thyroxine-binding globulin (TBG), thyroxine-binding pre-albumin (TBPA), and albumin.

Question 13

What happens after T4 crosses the cell membrane?

Answer 13

It gets deiodinated into T3 (the active form).

Question 14

What occurs with the thyroid hormones with subclinical hypothyroidism?

Answer 14

The TSH is minimally increased while the free T4 stays within normal range.

Question 15

What occurs with the thyroid hormones with subclinical hyperthyroidism?

Answer 15

The TSH is low while the free T4 is normal.

Question 16

Thyroglobulin is a protein synthesized and secreted exclusively by what types of cells?

Answer 16

Thyroid follicular cells.

Question 17

What antibodies can interfere with thyroglobulin results?

Answer 17

Antithyroglobulin autoantibodies.

Question 18

What is the most common cause of hyperthyroidism is an autoimmune disorder called what?

Answer 18

Graves’ disease.

Question 19

Define Graves’ Disease.

Answer 19

An autoimmune disorder that results in the overproduction of thyroid hormones (hyperthyroidism).

Question 20

in Graves’ Disease, antibodies in this condition are directed at which receptor?

Answer 20

TSH receptor (TSHR).

Question 21

In Graves’ disease, stimulating the TSH receptor leads to what?

Answer 21

Leads to growth of the thyroid gland and production of excessive amounts of thyroid hormone.

Question 22

With chronic lymphocytic thyroiditis (Hashimoto’s thyroiditis), how do antibodies effect thyroid hormones?

Answer 22

Antibodies lead to decreased thyroid hormone production by destruction of the thyroid gland.

Question 23

What diagnostic technique is often the first step and most accurate tool in evaluation of thyroid nodules in the absence of hyperthyroidism?

Answer 23

Fine-Needle Aspiration