Hyperthyroidism Flashcards
How would you treat primary hypothyroidism with medication?
- Replace thyroxine
- With levothyroxine
- Increase dose until TSH levels fall to normal
What is Grave’s disease?
*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
What are key/ sepcific features of Graves disease?
- Exophthalmos
Other AB’s bind to the muscles behind the eye and causes overgrowth - Pretibial myxoedema
Other antibodies cause hypertrophy- swelling (non-pitting) that occurs on the shins of patients: growth of soft tissue - Enlargement of the thyroid gland- goitre
How would you diagnose Grave’s disease?
Radioactive iodine scan: both lobes appear in scan- uniform radioiodine uptake
What is Plummer’s disease?
- 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
How would you diagnose Plummer’s disease?
Radioactive iodine scan: nodule/ mass growth only seen on one side in scan- radioiodine uptake not uniform
What effect does thyroxine have on the sympathetic nervous system?
- 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
What are the symptoms of hyperthyroidism?
*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
What is thyroid storm?
-Hyperthyroidism has gone untreated for a long time
-Medical emergency : 50% mortality
untreated
-Blood results confirm
hyperthyroidism
How would you diagnose thyroid storm?
Need 2 of the following symptoms:
Hyperpyrexia > 41C
*accelerated tachycardia / arrhythmia
*cardiac failure
*delirium / frank psychosis
*hepatocellular dysfunction; jaundice
*needs aggresive treatment
What are the treatment options for hyperthyroidism?
- Surgery (partial thyroidectomy)
- Radioiodine
- Drugs
What drugs are used to treat hyperthyroidism?
“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
Describe the action of thionamides
- 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)
What are the disadvantages of taking thionamides?
- 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
What is thyrotoxicosis?
Another term for hyperthyroidism
What is the role of b blockers in treatment of hyperthyroidism?
- Achieves effects much faster than anti-thyroid drugs
- prevent affects of adrenaline
What is the role of ioidide in treatment of hyperthyroidism?
- 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
What are some disadvantages to surgery?
- 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
What are some disadvantages of radioiodine capsule?
- Swallow a radioactive capsule
- Patients need to avoid children and pregnant mums for 1 week
- Used for scans only- not treatment
What is Viral (de Quervain’s) thyroiditis
Virus infects the thyroid grand
- damages follicle
- releases thyroxine suddenly (in 5mins)
What are the symptoms of Viral (de Quervain’s) thyroiditis in the first month?
*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)
How would you diagnose Viral (de Quervain’s) thyroiditis
Radioactive iodine scan: No more thyroxine synthesis- NO iodine uptake (zero)- nothing seen on the scan
What are the symptoms of Viral (de Quervain’s) thyroiditis in the second month?
- Eventually gland runs out of stores of thyroxine & none are being made (just virus)
- Switch from hyper to hypothyroidism
-lasts a second month
What are the symptoms of Viral (de Quervain’s) thyroiditis in the last/ third month?
*After a further month, resolution occurs (like in all viral diseases).
*Patient then becomes euthyroid (normal thyroid function) again- slow recovery
What is postpartum thyroiditis?
- similar (inflammation of the thyroid) but no pain and only occurs after pregnancy
- Most do not recover- immune system changes/ weakens during pregnancy
