Endocrine A

Question 1

What are the 2 hormones produced by the thyroid?

Answer 1

T3 and T4

Question 2

Which thyroid hormone accounts for most of the activity?

Answer 2

T3.

Question 3

How is thyroid hormone regulated?

Answer 3

TRH released from hypothalamus, TSH released from pituitary and T3 and T4 released from thyroid gland.

Question 4

What is the difference between T3 and T4?

Answer 4

T3 more potent, more rapidly degraded, faster acting, less of it.

Question 5

What are the 3 proteins that total T3 and T4 are bound to?

Answer 5

TBG
Albumin
TBPA

Question 6

How does change in protein levels change thyroid hormone activity?

Answer 6

It doesn’t because only the free T3 and T4 are active. Increased protein may change the levels of total T3 and T4 but not the free T3 and T4.

Question 7

What are the 2 main functions of thyroid hormones?

Answer 7

Increase basal metabolic rate, increasing oxygen consumption in tissues. To stimulate growth in children.

Question 8

What are the 3 main states of thyroid function?

Answer 8

Hyperthyroidism
Euthyroidism
Hypothyroidism

Question 9

What are thyroid nodules associated with?

Answer 9

Iodine deficiency
Hashimotos
Adenoma
Cyst in thyroid tissue

Question 10

What does iodine deficiency do?

Answer 10

Iodine is required to produce T3 and T4 so without it you get decreased T3 and T4 production. This is compensated by more TSH being produced by the pituitary so the person is in euthyroid state but the excess TSH causes oxidative damage which results in hyperplasia of the thyroid gland and goitre.

Question 11

What is hashimotos disease?

Answer 11

An autoimmune disease that commonly affects women over 40. The thyroid gland is gradually destroyed decreasing the production of T3 and T4 leading to hypothyroidism.

Question 12

What are the clinical symptoms of hashimotos disease?

Answer 12

Fatigue, increased sensitivity to cold, pale dry skin, unexplained weight gain, muscle weakness, goitre, increased risk of cardiovascular disease and increased risk of lymphoma.

Question 13

How does hashimotos disease happen?

Answer 13

Usually by a virus or genetic factor which triggers the immune system to attach the cells of the thyroid gland.

Question 14

What is a thyroid adenoma?

Answer 14

A benign tumour which can be functional or non-functional either causing euthyroid or hyperthyroidism.

Question 15

What is graves disease?

Answer 15

An autoimmune disease which stimulates the release of T4 and T3 from the thyroid gland results in hyperthyroidism and an enlarged thyroid.

Question 16

What are the clinical symptoms of graves disease?

Answer 16

Anxiety and irritability, tremor, heat sensitivity, unexplained weight loss, frequent bowel movement, bulging eyes, fatigue, thick red skin on tops of feet, rapid or irregular heartbeat.

Question 17

What is primary disease?

Answer 17

A dysfunction that occurs in the thyroid gland which leads to an increase or decrease in T3 or T4. Such as hashimotos, iodine deficiency, adenoma, graves disease.

Question 18

What is secondary disease?

Answer 18

A dysfunction that occurs outside of the thyroid gland but affects the thyroid leading to an increase or decrease in T3 and T4. This could be due to the patient taking medication or an adenoma in the pituitary producing TSH.

Question 19

What radioactive imaging pattern would you see with normal thyroid?

Answer 19

Diffuse stain

Question 20

What radioactive imaging pattern would you see with adenoma?

Answer 20

A mass of stain

Question 21

What radioactive imaging would you see with graves disease?

Answer 21

Increased staining but still diffuse.

Question 22

What radioactive imagining would you see with iodine deficiency?

Answer 22

Hot and cold nodules.