Thyroid disorders Flashcards Preview

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Flashcards in Thyroid disorders Deck (20):
1

How can we classify thyroid disorders?

Based on symptoms

Based on causes

2

Why is classification of thyroid disorders based on symptoms not useful?

Tells us nothing about the mechanism of the disease

Solely whether it is hyperthyroidism or hypothyroidism

3

What are possible causes of thyroid disorders?

Iodide deficiency

Autoimmunity

Neoplasia - thyroid cancer/ nodule formation

4

What is the most common cause of thyroid disorders?

Iodide deficienct

Affects 2.7% of the population

Easily treated - add dietary salt or supplementation

Most common in underdeveloped areas

5

What is the consequence of iodide deficiency?

Enlarged thyroid gland -> goitre

6

What gland regulates TH synthesis?

Pituitary

7

What hormone regulates TH synthesis?

TSH

8

What happens when TH are larger than required?

Negative feedback loop

TH send negative feedback to the hypothalamus pituitary axis to decrease TSH release

9

What happens to TH synthesis in iodide deficiency?

Low T3 and T4 means negative feedback loop is compromised

Has long-term and short-term effects

1. Short-term effect: TSH release T3 and T4 from gland stores

2. Long-term effects: TSH enhances proliferation of thyroid cells = enlargement of thyroid gland and formation of goitre

10

What is the compensatory mechanism for formation of a goitre?

Ensures the gland absorbs all iodine from the circulation

11

What is a multinodular goitre?

Over time the large thyroid can develop nodules

12

What two autoimmune diseases affect the thyroid?

Grave's disease

Thyroiditis

13

How do Thyroiditis and Grave's differ?

Thyroiditis = autoantigens formed against the thyroid - leads to destruction and inflammation of the gland. Decreased TH levels

Grave's = autoantigens are complementary for TSH receptors on gland. Increased TH levels.

14

Pathogenesis of thyroiditis

Destruction of thyroid gland by inflammatory cells

Antibodies against thyroid gland taget the cells

Infiltration of inflammatory cells - neutrophils and macrophages

Secretion of inflammatory mediators - induce damage to the thyroid cells

Inflammation and destruction of thyroid gland

15

What does Thyroiditis cause?

Hypothyroidism

16

Pathogenesis of Grave's disease

Formation of autoantibodies targeted against TSH receptor

Agonist to TSH and causes release og T3 and T4

17

What does Grave's cause?

Hyperthyroidism

18

What are symptoms of Grave's?

Exophthalmos

Fat tissue in the eyes express TSH receptors

Proliferation of the cells in the orbit upon activation

19

Treatment of Hypothyroidism

Thyroxine structure is simple - easy to synthesise synthetically

Injection of supplements

20

Treatment of Hyperthyroidism

More complicated

1. Inhibition of TH synthesis by inhibition of TPO

2. Ablation - if the patient doesn't respond to pharmacological inhibition

3. Surgical or radioactive iodine