Thyroid: Tests and Complications

Question 1

Explain the thyroid axis

Answer 1

Question 2

What hormone does the hypothalamus produce?

Answer 2

TRH

TRH stands for Thyrotropin-Releasing Hormone.

Question 3

What hormone does the anterior pituitary gland produce?

Answer 3

TSH

TSH stands for Thyroid-Stimulating Hormone.

Question 4

Which hormones are produced by the thyroid gland?

Answer 4

T3 (triiodothyronine), T4 (Thyroxine)

T3 and T4 are critical for regulating metabolism.

Question 5

What type of feedback is associated with TRH and TSH leading to T3 and T4 production?

Answer 5

Positive feedback

This process enhances the production of thyroid hormones.

Question 6

What type of feedback occurs when T3 and T4 levels lead to decreased TRH and TSH?

Answer 6

Negative feedback

This mechanism helps maintain hormone balance.

Question 7

What is the primary screening test for thyroid disease?

Answer 7

TSH

An abnormal TSH level indicates potential thyroid issues.

Question 8

What should be measured if TSH is abnormal?

Answer 8

T3 and T4

These tests help diagnose the specific thyroid condition.

Question 9

What is primary hyperthyroidism characterized by?

Answer 9

HIGH T3 and T4, causing LOW TSH

Indicates overproduction of thyroid hormones.

Question 10

What are the causes of primary hyperthyroidism represented by ‘GIST’?

Answer 10

• Graves’ disease
• Inflammatory (thyroiditis)
• Solitary toxic thyroid nodule
• Toxic multinodular goitre

These conditions lead to excessive thyroid hormone production.

Question 11

What is secondary hyperthyroidism characterized by?

Answer 11

Excessive HIGH TSH, causing HIGH T3 and T4

This is due to pituitary gland dysfunction.

Question 12

What is a common cause of secondary hyperthyroidism?

Answer 12

Pituitary adenoma

A tumor in the pituitary gland can lead to excessive TSH production.

Question 13

What is primary hypothyroidism characterized by?

Answer 13

Inadequate hormones with LOW T3 and T4, HIGH TSH

Indicates a failure of the thyroid gland.

Question 14

What are the causes of primary hypothyroidism?

Answer 14

• Hashimoto’s thyroiditis
• Iodine deficiency
• Treatments for hyperthyroidism

These factors can impair thyroid hormone production.

Question 15

What is secondary hypothyroidism characterized by?

Answer 15

LOW TSH, LOW T3 and T4

This results from inadequate stimulation of the thyroid gland.

Question 16

What is a common cause of secondary hypothyroidism?

Answer 16

Pituitary gland removal

Surgical removal can lead to decreased TSH production.

Question 17

What characterizes subclinical hypothyroidism?

Answer 17

TSH HIGH, T4 normal

Indicates early thyroid dysfunction without overt symptoms.