Thyroid disorders

Question 1

Explain why palpitations in isolation, may not be a symptom of hyperthyroidism

Answer 1

Could be due to stress or lack of sleep.

Question 2

Why are females more likely to suffer from hyperthyroidism

Answer 2

Females have a less stringent recognition of self, so that the baby is not rejected.

Question 3

What is the effect of T4 and T3 on catecholamines

Answer 3

They potentiate the effect of catecholamines, hence adrenaline has an enhanced effect. This may explain the increased heart rate.

Question 4

What does the fact the thyroid is extended symmetrically either side of the midline indicate

Answer 4

Unlikely to be a tumour of the thyroid gland.

Question 5

Why do patients with hypothyroidism have irregular periods

Answer 5

Low t3 and T4 disrupts menstrual cycles, resulting in irregular cycles, hence when they menstruate, they are normally heavier. Lack of inhibition of TRH. TRH stimulates prolactin release. Consequently, prolactin inhibits pituitary gonadotrophin production resulting in decreased gonadal hormone production by the ovaries.

Question 6

Why may patients with hypothyroidism be pale

Answer 6

Low tissue perfusion, hence blood supply moves away from the skin. This may be confused with anaemia.

Question 7

What may patients who are really hypothyroid present with

Answer 7

Slow reflexes

Question 8

Why is it important to determine the cause of the problem

Answer 8

High TSH could be due to tumour of the pituitary gland, and presents similarly to hypothyroidism, hence this must be excluded.

Question 9

What is a deepened voice in hypothyroidism due to

Answer 9

Thickening of the vocal cords due to the retention of mucopolysaccharides and other water-retaining molecules ( which would also account for the puffiness of the skin observed).

Question 10

Why do patients with hypothyroidism sometimes present with yellowish skin

Answer 10

Decreased synthesis of vitamin A from carotene which consequently can build up in the circulation giving the skin a yellowish colour. This can be distinguished from jaundice, as in hypothyroidism, the sclera of the eye does not become equally tinged.

Question 11

What other symptoms are common in hypothyroidism

Answer 11

Alopecia (manifests in loss of outer third of eyebrows)

Increased incidence of depression.