Endocrinology 7 - Thyroid Disorders

Question 1

Where is the thyroid gland located?

Answer 1

• At the back of the tongue, starting in the embryo at the thyroglossal duct.
• It migrates down the neck.

Question 2

Describe the basic anatomy of the thyroid gland.

Answer 2

• A shield shape
• Pyramidal lobe comes out the top
• Right and left lobes
• Isthmus in the middle
• 4 parathyroid glands

Question 3

What is the foramen caecum?

Answer 3

A dimple at the back of the tongue, the reminant of the thyroglossal duct.

Question 4

What is the weight of the adult thyroid gland?

Answer 4

20g

Question 5

How many lobes are there in the thyroid gland? Which is the largest?

Answer 5

• Four lobes, the right is the largest

- Each lobe is around 4 x 2.5 x 2.5

Question 6

What glands are found embedded in the thyroid?

Answer 6

Parathyroid glands

Question 7

What important nerve runs very close to the thyroid gland and what does it supply?

Answer 7

Laryngeal nerve, which supplies the muscles of the larynx.

Question 8

List the problems that can occur in the development of the thyroid

Answer 8

• Agenesis (complete absense)
• Incomplete descent
• Thyroglossal cyst (segment of the duct persists and forms a cyst)

Question 9

What term is used to describe an individual who has irreversible brain damage caused by lack of thyroxine in fetal and neonatal life?

Answer 9

Cretin

Question 10

Why are thyroid diseases more common in females?

Answer 10

• Autoimmune diseases are more common in females

- This is because women have a greater immune response than men

Question 11

What can cause primary hypothyroidism?

Answer 11

• Autoimmune disease

- Surgeon removing the thyroid gland

Question 12

What is another name for primary hypothyroidism?

Answer 12

Myxoedema

Question 13

Describe the biochemical findings in a patient with hypothyroidism.

Answer 13

• No thyroxine

- High levels of TSH

Question 14

List the features of primary hypothyroidism

Answer 14

• Deepening voice (cartilage vibrations slow)
• Depression and tiredness
• Cold intolerance (lower BMR - basal metabolic rate)
• Weight gain with decreased appetite
• Constipation
• Bradycardia (lowered heart rate)
• Heavy and longer period
• Eventually unconscious (eventual myxoedema coma)

Question 15

Why is treatment of hypothyroidism essential?

Answer 15

• Can result in myxoedema coma, and death.

- Cholesterol also goes up.

Question 16

What is the treatment of hypothyroidism?

Answer 16

• Daily dose of thyroxine.

- The levels of TSH are measured until levels become normal.

Question 17

What is another name for hyperthyroidism?

Answer 17

Thyrotoxicosis

Question 18

What are the biocemical findings in an individual with hyperthyroidism?

Answer 18

• Too much thyroxine
• TSH falls to 0
• Basal metabolic rate increases

Question 19

What causes hyperthyroidism?

Answer 19

• Graves disease - immune system makes an antibody to stimulate the receptor in the thyroid gland to make more thyroxine, despite lack of TSH
• The whole gland grows

Question 20

List the features of an overactive thyroid gland

Answer 20

• Confused, irrational, mood swings
• Myopathy (weakness due to protein breakdown), aching joints
• Difficulty sleeping - tired but too wired up
• Feeling hot all the time
• Diarrhoea
• Weight loss with large appetite
• Tremour
• Palpatations
• Sore eyes
• Goitre (swelling of the thyroid gland)

Question 21

Describe the features of graves disease.

Answer 21

• Thyroid gland is smoothly enlarged

- Pretibial myxoedema (swelling of the shins - not myxoedema as in hypothyroidism)