Treatment of Thyroid Disorders

Question 1

Name the three hormones secreted by the thyroid gland

Answer 1

Thyroxine
Triiodothyronine
Calcitonin

Question 2

What are the main steps involved in the synthesis of thyroid hormones?

Answer 2

1. Uptake of plasma iodide by the follicle cells.
2. Oxidation of iodide and iodination of tyrosine residues in thyroglobulin of the colloid.
3. Secretion of the thyroid hormone

Question 3

Describe some features of hypothyroidism

Answer 3

• Low free T4, possibly low T3 and raised TSH.

- Long term complications include cardiovascular disease

Question 4

What are some of the causes of hypothyroidism?

Answer 4

Congenital,
Autoimmune thyroiditis,
Iatrogenic (post thyroidectomy or radio-iodine treatment),
Drug induced (lithium, amiodarone),
Pituitary disease

Question 5

What are the causes of congenital hypothyroidism

Answer 5

• Absent thyroid (agenesis),
• Under developed (dysgenesis),
• Familial enzyme defects,
• Iodine deficiency,
• Intake of goitrogens during pregnancy,
• Idiopathic.
  All babies are screened for hypothyroidism at birth

Question 6

Describe features of Hashimoto’s?

Answer 6

• Most common cause of hypothyroidism,

- Autoimmune lymphocytic thyroiditis

Question 7

Describe the relationship between amiodarone and the thyroid

Answer 7

Amiodarone has very close structural resemblance to thyroid hormones

Question 8

What are the symptoms of hypothyroidism

Answer 8

• Tiredness,
• Weight gain,
• Feeling cold,
• Constipation,
• Dry or thinning hair,
• Hoarse voice,
• Pins and needles,
• Low mood,
• Memory problems

Question 9

Explain the management of primary hypothyroidism

Answer 9

• Levothyroxine (synthetic analogue of thyroxine.

- Aim to maintain TSH within reference range.

Question 10

What are the causes of hyperthyroidism

Answer 10

• Autoimmune (Graves),
• Toxic multinodular goiter,
• de Quervain’s thyroiditis,
• Medication (overtreatment with levothyroxine),
• Pituitary adenoma (tumour producing excess TSH),
• Transient neonatal thyrotoxicosis (mother with graves).
• Thyroid adenoma (rare)

Question 11

Describe features of graves disease

Answer 11

• Autoimmune disorder mediated by antibodies that stimulate TSH.
• Clinical features are diffuse goitre, pretibial myxoedema, thyroid eye disease and acropathy.

Question 12

Describe features of toxic multinodular goitre

Answer 12

• Small benign nodules within the thyroid gland. They are unresponsive to secretory control mechanisms and therefore secrete excess T3 and T4.
• Iodine deficiency is the most common cause

Question 13

Describe features of de Quervain’s (subacute thyroiditis)

Answer 13

Painful swelling of thyroid gland triggered by a viral infection.

Question 14

What are the symptoms of hyperthyroidism

Answer 14

• Anxiety,
• Palpitations,
• Weight loss,
• Goitre,
• Hair loss,
• Fatigue,
• Diarrhoea,
• Sweating,
• Muscle weakness,
• Insomnia,
• Periods are lighter/infrequent

Question 15

What are the treatments for hyperthyroidism?

Answer 15

• Radioactive iodine,
• Anti thyroid medications,
• Symptomatic treatment,
• Surgery

Question 16

What is the first line anti-thyroid drug and its features?

Answer 16

Carbimazole which gets metabolised to methimazole which directly inhibits thyroid hormone synthesis. Does this by inhibition of thyroperoxidase which reduces iodination of thyroglobulin.
May take several weeks to work

Question 17

What are the main side effects of carbimazole

Answer 17

• Neutropenia and agranulocytosis,
• Skin rashes,
• Pancreatitis
• Increased risk of congenital malformations

Question 18

What is the 2nd line treatment and its features

Answer 18

Propylthiouracil. Given to patients who experience side effects with carbimazole or pregnant/trying to conceive.
Side effects - agranulocytosis, bone marrow disorders, hepatic impairment.

Question 19

What are other medications used in hyperthyroidism?

Answer 19

Thyroid hormones increase number of receptors, particular beta adrenoceptors which causes tachycardia, hypertension and increased risk of dysrhythmias, tremors, and agitation. So beta blockers such as propranolol is often used adjunct to anti-thyroid therapy

Question 20

When is surgery appropriate for hyperthyroidism?

Answer 20

• Total thyroidectomy for adults with grave’s disease

Question 21

What are potential complications of thyroid surgery?

Answer 21

• Haemorrhage, infection, damage to laryngeal nerve, hypothyroidism, hypocalcaemia, hypoparathyroidism

Question 22

Describe features of radioactive iodine?

Answer 22

It is given orally and is selectively taken up by thyroid.

• Given as single dose which lasts 2 months.
• Not suitable before puberty.
• Avoid contact with pregnant women and small children.

Question 23

What is the block and replace regimen?

Answer 23

High dose carbimazole with levothyroxine.