Hypothyroidism

Question 1

1) What is the commonest cause of hypothyroidism?
2) What is the pathophysiology of this condition?

Answer 1

1) Hashimoto’s thyroiditis
2) Autoimmune inflammation of the thyroid gland which causes goitre then atrophy of the thyroid gland

Question 2

1) What is the commonest cause of hypothyroidism in the developing world?
2) Name another cause of hypothyroidism?

Answer 2

1) Iodine deficiency
2) Treatments for hyperthyroidism (carbimazole, propylthiouracil, radioactive iodine, thyroid surgery) and other medications i.e. lithium, amiodarone

Question 3

1) What is the cause of a secondary hypothyroidism?
2) Name 2 causes of this

Answer 3

1) When the pituitary gland is failing and producing less TSH (hypopituitarism)
2) Tumour, infection, radiation, vascular (Sheehan syndrome)

Question 4

Name 3 ways hypothyroidism can present

Answer 4

• Weight gain
• Fatigue
• Dry skin
• Coarse hair and hair loss
• Fluid retention (oedema, pleural effusions, ascites)
• Heavy or irregular periods
• Constipation

Question 5

1) In primary hypothyroidism, what will the levels of T3, T4 and TSH be, and why?
2) In secondary hypothyroidism, what will the levels of T3, T4 and TSH be, and why?

Answer 5

1) Low T3 and T4 (damage to the gland) but high TSH as there’s no negative feedback, so the pituitary produces lots of TSH
2) Low TSH (pituitary pathology) and low T3 and T4 (low TSH)

Question 6

1) How is hypothyroidism managed?
2) What is this and what happens to it in the body?

Answer 6

1) Levothyroxine
2) Synthetic T4 and is metabolised to T3 in the body

Question 7

What marker is used to assess response to treatment with levothyroxine?

Answer 7

TSH levels