Treatment of Thyroid Disorders

Question 1

What results would you see in TFTs in hypothyroidism

Answer 1

• low T4 (and possibly T3)

- raised TSH

Question 2

List the causes of hypothyroidism

Answer 2

• congenital
• autoimmune (Hashimoto’s)
• iatrogenic (post thyroidectomy or radio-iodine treatment)
• drug induced (anti-thyroid medications, lithium, amiodarone)
• pituitary disease

Question 3

List the causes of congenital hypothyroidism

Answer 3

• absent thyroid (agenesis)
• underdeveloped thyroid (dysgenesis)
• familial enzyme defects
• iodine deficiency
• intake of goitrogens in pregnancy
• pituitary defects
• idiopathic

Question 4

What are the complications of untreated congenital hypothyroidism?

Answer 4

impaired brain development and low IQ

Question 5

Explain how amiodarone can cause hypothyroidism

Answer 5

• close structural resemblance to thyroid hormones

- long-term treatment associated with increases in plasma and urinary iodide levels

Question 6

Describe the management of primary hypothyroidism

Answer 6

• levothyroxine
• 1.6mg/kg per day (to nearest 25mg) for adults under 65 and no history of CVD
• 25-50mg per day for over 65s or history of CVD and titrate
• check TFTs after 6 weeks

Question 7

What results would you expect to see in TFTs of hyperthyroidism

Answer 7

• raised T3 and T4

- low TSH

Question 8

List the causes of hyperthyroidism

Answer 8

• autoimmune (Graves)
• toxic multinodular goitre
• de Quervain’s (subacute) thyroiditis
• pituitary adenoma (producing TSH)
• transient neonatal thyrotoxicosis (mother with Graves)
• thyroid adenoma (rare)
• medication (overtreatment with levothyroxine)

Question 9

What is a toxic multinodular goitre?

Answer 9

• small benign nodules within the thyroid gland
• cells within the nodules are unresponsive to secretory mechanisms and secrete excess T3 and T4
  (iodine deficiency most common cause worldwide)

Question 10

What is de Quervain’s subacute thyroiditis?

Answer 10

• painful swelling of the thyroid gland

- triggered by viral infection

Question 11

What is the treatment for hyperthyroidism?

Answer 11

• radioactive iodine
• anti-thyroid medication
• symptomatic medication
• surgery

Question 12

Describe radioactive iodine treatment

Answer 12

• given orally and selectively taken up by the thyroid gland
• single dose that lasts 2 months
• accumulated in follicular cells of thyroid gland and as it decays the beta particle emissions destroy the surrounding tissue

Question 13

Describe the pharmacological treatment of hyperthyroidism

Answer 13

• propylthioracil (200-400mg daily until euthyroid and decreased) and carbimazole directly inhibit thyroid hormone synthesis (inhibit thyroperoxidase preventing iodination of thyroglobulin)
• carbimazole is first line (15-40mg daily until patient is euthyroid then reduced to 5-15mg daily for 12-18 months)

Question 14

What are the side effects of carbimazole?

Answer 14

• neutropenia and agranulocytosis
  (advise patients to report signs and symptoms of infection, esp sore throat and do white cell count)
• pancreatitis
• skin rashes

Question 15

What are the side effects of propylthiouracil?

Answer 15

• agranulocytosis
• hepatic impairment
• bone marrow disorders
  (risk of enhanced effects if given with drug that competes binding to albumin eg. warfarin and NSAIDs)

Question 16

What symptomatic medications are used in hyperthyroidism?

Answer 16

• B-blockers eg. propranolol (counteract tachycardia, hypertension, skeletal muscle tremor, agitation)

Question 17

What are the potential complications of surgery?

Answer 17

• haemorrhage
• infection
• damage to laryngeal nerve
• hypothyroidism
• hypocalcaemia
• hypoparathyroidism