7 - Thyroid Disorders

Question 1

What are two features of cretinism?

Answer 1

• stunted growth

- low IQ

Question 2

What is the anatomy of the thyroid gland?

Answer 2

• shield-shaped
• 4 lobes
• at back of tongue at back of neck
• 4 parathyroid glands embedded
• left recurrent laryngeal nerve runs close to thyroid (vocal cord supply)

Question 3

What are the 4 lobes of the thyroid?

Answer 3

• right (biggest)
• left
• pyramidal
• isthmus

Question 4

What is the embryology of the thyroid?

Answer 4

• midline outpouching of floor of pharynx
• origin at base of tongue
• forms thyroglossal duct which elongates down neck and divides into 2 lobes
• final position by week 7
• duct disappears when in position and leaves foramen caecum
• thyroid gland then develops

Question 5

What is agenesis?

Answer 5

complete absence of thyroid

Question 6

What is a cretin?

Answer 6

an individual with irreversible brain damage caused by lack of thyroxine

Question 7

What are some issues with the development of the thyroid?

Answer 7

• incomplete descent (between base of tongue and trachea)

- thyroglossal cyst may form (segment of duct persists and presents as lump years later)

Question 8

What is primary hypothyroidism (myxoedema)?

Answer 8

• primary thyroid failure
• caused by autoimmune damage to thyroid or through accidental removal in surgery
• thyroxine levels decline
• TSH levels climb

Question 9

What are the features of myxoedema?

Answer 9

• deepening voice
• depression and tiredness
• cold intolerance
• weight gain with reduced appetite
• constipation
• bradycardia
• eventual myxoedema coma

Question 10

What is the treatment for myxoedema?

Answer 10

• replace thyroxine with 100mg tablet daily

- TSH monitored and dose adjusted accordingly

Question 11

What is an overactive thyroid gland?

Answer 11

• makes too much thyroxine and TSH levels fall to zero

- hyperthyroidism/thyrotoxicosis

Question 12

What are the internal features of an overactive thyroid gland?

Answer 12

• raised basal metabolic rate
• raised temperature
• calories burnt up and weight loss
• increased heart rate

Question 13

What are the external symptoms of an overactive thyroid gland?

Answer 13

• myopathy
• mood swings
• hot in all weather
• diarrhoea
• increased appetite with weight loss
• hand tremors
• palpitations
• sore eyes

Question 14

What is graves’ disease and its features?

Answer 14

• whole thyroid gland is smoothly enlarged and overactive
• autoimmune
• antibodies bind to and stimulate TSH receptor in thyroid
• causes hyperthyroidism
• other antibodies bind to muscles behind eye and cause exopthalamos or stimulate growth of shins to cause hypertrophy

Question 15

What is pretibial myxoedema?

Answer 15

• growth of soft tissue on shins