Thyroid

Question 1

Describe the thyroid axis?

Answer 1

• Hypothalamus releases TRH
• TRH stimulates anterior pituitary to release TSH
• TSH stimulates thyroid to produce T4 and T3
• (T4 provides negative feedback to hypothalamus)

Question 2

Describe Primary hypothyroidism?

Answer 2

• Reduced T4 from thyroid gland itself
• Pathology of the thyroid gland
• Raised TSH

Question 3

Describe Subclinical hypothyroidism?

Answer 3

• Normal T4
• Raised TSH

Question 4

Describe Secondary hypothyroidism?

Answer 4

• Reduced TRH or TSH
• Pathology of the pituitary or hypothalamus

Question 5

Pituitary causes of secondary hypothyroidism?

Answer 5

• Adenoma
• Surgery/radiotherapy

Question 6

Hypothalamic causes of secondary hypothyroidism?

Answer 6

• Hypothalamus tumour
• Surgery/radiation history

Question 7

Causes of primary HYPERthyroidism?

Answer 7

• Graves disease
• Toxic adenoma
• Toxic multinodular goitre

Question 8

Causes of secondary HYPERthyroidism?

Answer 8

• TSH-secreting tumour
• hCG-secreting tumour