Hyperthyroidism

Question 1

How would you treat primary hypothyroidism with medication?

Answer 1

• Replace thyroxine
• With levothyroxine
• Increase dose until TSH levels fall to normal

Question 2

What is Grave’s disease?

Answer 2

*Autoimmune (immune system attacks thyroid and makes it overactive)
*Antibodies bind to and stimulate the TSH receptor in the thyroid- mimic TSH; all cells speed up
*Cause goitre (smooth) and hyperthyroidism

Question 3

What are key/ sepcific features of Graves disease?

Answer 3

1. Exophthalmos
   Other AB’s bind to the muscles behind the eye and causes overgrowth
2. Pretibial myxoedema
   Other antibodies cause hypertrophy- swelling (non-pitting) that occurs on the shins of patients: growth of soft tissue
3. Enlargement of the thyroid gland- goitre

Question 4

How would you diagnose Grave’s disease?

Answer 4

Radioactive iodine scan: both lobes appear in scan- uniform radioiodine uptake

Question 5

What is Plummer’s disease?

Answer 5

• Nodule (benign tumour) that is overactive at making thyroxine
• not autoimmne; no pretibial myxoedema and no exophthalmos
• More common than Grave’s
• Especially common in elderly

Question 6

How would you diagnose Plummer’s disease?

Answer 6

Radioactive iodine scan: nodule/ mass growth only seen on one side in scan- radioiodine uptake not uniform

Question 7

What effect does thyroxine have on the sympathetic nervous system?

Answer 7

• Sensitises beta adrenoceptors to ambient levels of adrenaline and noradrenaline
• Someone with hyperthyroidism is very sensitive to adrenaline (easily scared, tremour, tachycardia, palpitations)
• Causes Lid lag
  -NOTE: does not mean they have too much adrenaline- just highly sensitive to it

Question 8

What are the symptoms of hyperthyroidism?

Answer 8

*Weight loss despite increased appetite
*Breathlessness,
*palpitations, tachycardia
*Sweating
*Heat intolerance
*Diarrhoea
*Lid lag and other sympathetic features
*Tiredness despite adrenaline- don’t get enough sleep

Question 9

What is thyroid storm?

Answer 9

-Hyperthyroidism has gone untreated for a long time
-Medical emergency : 50% mortality
untreated
-Blood results confirm
hyperthyroidism

Question 10

How would you diagnose thyroid storm?

Answer 10

Need 2 of the following symptoms:
Hyperpyrexia > 41C
*accelerated tachycardia / arrhythmia
*cardiac failure
*delirium / frank psychosis
*hepatocellular dysfunction; jaundice
*needs aggresive treatment

Question 11

What are the treatment options for hyperthyroidism?

Answer 11

1. Surgery (partial thyroidectomy)
2. Radioiodine
3. Drugs

Question 12

What drugs are used to treat hyperthyroidism?

Answer 12

“Reduce thyroid hormone synthesis”:
1. The thionamides (thiourylenes; anti-thyroid drugs)
- propylthiouracil (PTU)
- carbimazole (CBZ)
2. Potassium Iodide
3. Radioiodine

“B blockers help with symptoms; adrenaline”
4. β-blockers (e.g. propranolol)- given first to reduce symptoms

Question 13

Describe the action of thionamides

Answer 13

• Inhibition of thyroid peroxidase and hence T3/ T4 synthesis and secretion
• Has immediate biochemical effects (within Hrs)
• The clinical effects take longer (weeks)- there are still stores of thyroxine/ need to run out
• Usually aim to stop anti-thyroid drug treatment after 18 months
• Review patient periodically including thyroid function tests for remission/relapse (options: use tablets forever, radiotherapy, surgery)

Question 14

What are the disadvantages of taking thionamides?

Answer 14

• Agranulocytosis (usually reduction in
  neutrophils) - rare and reversible on
  withdrawal of drug.
• rashes (relatively common)
• causes pain in the throat- indicates patients need WBC count

Question 15

What is thyrotoxicosis?

Answer 15

Another term for hyperthyroidism

Question 16

What is the role of b blockers in treatment of hyperthyroidism?

Answer 16

• Achieves effects much faster than anti-thyroid drugs
• prevent affects of adrenaline

Question 17

What is the role of ioidide in treatment of hyperthyroidism?

Answer 17

• Usually given in doses as KI
• Used for preparation of hyperthyroid patients for surgery (reduces bleeding from thyroid- makes surgery easier)
• Used for severe thryotoxic crisis (thyroid storm)
• “Wolff-chaikoff effect”- inhibition of thyroid hormone synthesis & secretion
• Hyperthyroid symptoms reduce within 1-2 days
• vascularity and size of gland reduce within 10-14 days

Question 18

What are some disadvantages to surgery?

Answer 18

• Risk of voice change (can’t shout- voice remains quiet)- if laryngeal nerve damage- vocal cords affected
• Risk of also losing parathyroid glands
• Scar
• Anaesthetic

Question 19

What are some disadvantages of radioiodine capsule?

Answer 19

• Swallow a radioactive capsule
• Patients need to avoid children and pregnant mums for 1 week
• Used for scans only- not treatment

Question 20

What is Viral (de Quervain’s) thyroiditis

Answer 20

Virus infects the thyroid grand
- damages follicle
- releases thyroxine suddenly (in 5mins)

Question 21

What are the symptoms of Viral (de Quervain’s) thyroiditis in the first month?

Answer 21

*Painful dysphagia (virus attacks the thyroid gland)
*Hyperthyroidism (all stored thyroxine released, free T4 levels rise, TSH drops)
*Pyrexia (raised body temp)
*Thyroid inflammation
*Thyroid stops making thyroxine and makes viruses instead (no new thyroxine synthesised)

Question 22

How would you diagnose Viral (de Quervain’s) thyroiditis

Answer 22

Radioactive iodine scan: No more thyroxine synthesis- NO iodine uptake (zero)- nothing seen on the scan

Question 23

What are the symptoms of Viral (de Quervain’s) thyroiditis in the second month?

Answer 23

• Eventually gland runs out of stores of thyroxine & none are being made (just virus)
• Switch from hyper to hypothyroidism
  -lasts a second month

Question 24

What are the symptoms of Viral (de Quervain’s) thyroiditis in the last/ third month?

Answer 24

*After a further month, resolution occurs (like in all viral diseases).
*Patient then becomes euthyroid (normal thyroid function) again- slow recovery

Question 25

What is postpartum thyroiditis?

Answer 25

• similar (inflammation of the thyroid) but no pain and only occurs after pregnancy
• Most do not recover- immune system changes/ weakens during pregnancy