Thyroid

Question 1

Explain the release of T3 and T4

Answer 1

• Hypothalamus releases TRH (thyrotropin releasing hormone) which acts on the anterior pituitary gland
• Anterior pituitary gland releases TSH (thyroid stimulating hormone)
• Thyroid gland releases T3 and T4 (negative feedback on the anterior pituitary and the hypothalamus)

Question 2

What is the effect of T3 and T4?

Answer 2

• Increased metabolism (increases oxygen consumption and therefore heat)
• Growth and development
• Increased catecholamine effect

Question 3

How does T3 carry about its effects?

Answer 3

It enters the nucleus and then binds with coregulators and leads to changes in gene transcription

Question 4

What is Grave’s disease?

Answer 4

• Long acting thyroid stimulator - autoimmune stimulation of the thyroid
• Causes hypertrophy of the thyroid and hyperthyroidism

Question 5

What is Hashimotos?

Answer 5

• Autoimmune destruction of thyroid

* Atrophy of the thyroid and hypothyroidism

Question 6

What are the causes of hypothyroidism?

Answer 6

•Pituitary - hypopituitarism
•Thyroid:
- Thyroidectomy
- Post radioactive iodine ablation
- Autoimmune: Hashimoto’s, blocking TSH receptor antibodies, postpartum thyroiditis
- inborn errors: congenital hypothyroidism

Question 7

What are the signs of neonatal hypothyroidism

Answer 7

• Cretinism
• Coarse facial features
• Macroglossia
• Large fontanelles
• Umbilical hernia
• Mottled, cool, and dry skin
• Developmental delay
• Pallor
• Myxoedema
• Goitre

Question 8

What are the causes of congenital hypothyroidism?

Answer 8

•Thyroid degenesis: TSH receptor 
•Dyshormonogenesis 
 - thyroid peroxidase
 - thyroglobulin 
 - sodium iodide symporter 
 - pendrin (pendred syndrome)

Question 9

What are the signs/symptoms of hypothyroidism?

Answer 9

• Cold intolerance
• Weight gain and decreased apetitie
• Oedema
• Depression
• Low heart rate and BP
• Muscle cramps, myalgia
• Constipation (decreased GI motility)
• Skin pale, thick and dry
• Hair coarse and thick

Question 10

What are the symptoms of hyperthyroidism?

Answer 10

• Heat intolerance
• Weight loss and loss of muscle mass
• Irritability, restlessness, insomnia
• Exopthalmos in graves disease
• Rapid heart rate and high BP
• Diarrhoea, loss of appetite
• Flushed, thin and moist skin
• Nails soft and thin

Question 11

What signs would make you have graves as a leading diagnosis

Answer 11

Goitre with a bruit

Question 12

What are the investigations for hypothyroidism?

Answer 12

• Free T3 and T4
• TRH/TSH
• Thyroid peroxisomal antibody

Question 13

What is primary hypothyroidism?

Answer 13

Low levels of thyroid hormones due to destruction of the thyroid gland

Question 14

What is the treatment of hypothyroidism?

Answer 14

• L thyroxine (T4)

* 75-150mcg per day

Question 15

Explain the test results in primary hypothyroidism

Answer 15

• Normal/high TSH

* Low T4/T3

Question 16

What are the test results in secondary hypothyroidism?

Answer 16

• Low TSH
• Low T3/4
• High/normal TRH

Question 17

If someone presents with hyperthyroidism but is antibody negative what test should you do next?

Answer 17

Thyroid uptake scan

Question 18

Tests for hyperthyroidism

Answer 18

• TSH
• Free T4
• Total T3
• TSH receptor antibodies
• TPO - thyroid peroxisomal antibody

Question 19

What are the clinical signs of hyperthyroidism?

Answer 19

• Pretibial myxeoedma

* Thyroid acropachy ( on X ray)

Question 20

What is the treatment of hyperthyroidism?

Answer 20

• Beta blockers
• Carbimazole
• Radioactive iodine
• Thyroidectomy

Question 21

What are the complications of thyroidectomy?

Answer 21

• Bleeding
• Scar
• Recurrent laryngeal nerve palsy

Question 22

What is the aetiology of graves?

Answer 22

• Autoimmune disease
• Genetic susceptibility
• Environmental - iodine, tobacco smoking
• Immune modulating treatment: interferon, alemtuzemab (anti CD52 mAb)

Question 23

What antibodies are produced in graves?

Answer 23

Activating antibodies directed against the TSH receptor, activating it

Question 24

What are the antibodies that are produced in Hashimoto’s?

Answer 24

Thyroid peroxisomal antibodies

Question 25

What are the causes of hyperthyroidism?

Answer 25

•Pituitary - adenoma 
•Thyroid: 
 - autoimmune: activating TSH receptor antibodies (Graves), Thyroiditis acute early phase 
- thyroid adenoma
•Other hormones acting as TSH -HCG

Question 26

Which drug can cause both hyper and hypothyroidism?

Answer 26

Amiodarone

Question 27

What is the Job Basedow phenomenon?

Answer 27

Iodine induced hyperthyroidism

Question 28

What is the Wolff Chaikoff effect?

Answer 28

iodine induced hypothyroidism

Question 29

What is type 1 amiodarone thyroid disease?

Answer 29

•Autoimmune thyrotoxicosis

Question 30

What is type 2 amiodarone thyroid disease?

Answer 30

•Destructive thyroiditis

Question 31

What is the treatment of type 1 amiodarone thyroid disease?

Answer 31

High dose carbimazole

Question 32

What is the treatment of type 2 amiodarone thyroid disease?

Answer 32

Glucocorticoids

Question 33

What are the thyroid carcinomas?

Answer 33

• Papillary
• Follicular
• Anaplastic
• Poorly differentiated

Question 34

What is the grading of incidentalomas?

Answer 34

• U1 - normal
• U2 - benign
• U3
• U4
• U5

Question 35

Which diseases are associated with RET protooncogene?

Answer 35

• Familial medullary thyroid cancer
• Multiple endocrine neoplasia type 2 and 3 (pheochromocytoma, primary hyperparathyroidism, MTC)
• Hirschprungs