Hyperthyroidism Flashcards
TSH stimulates which processes?
uptake of iodine into the thyroid gland and proteolytic enzyme to release thyroxine from follicles into the bloodstream.
how much thyroxine is stored in the thyroid gland?
enough for 1 month
Body attacking thyroid so it cannot make T3 and T4 is an example of?
primary hypothyroidism
treatment for primary hypothyroidism
levothyroxine until TSH falls into normal range
What happens in graves disease?
antibodies bind to and stimulate TSH receptor in thyroid causing smooth goitre
graves disease is an example of?
primary hyperthyroidism
In Grave’s disease, what happens to the metabolism?
speeds up
which scan is used to diagnose graves disease, plummers disease and viral thyroiditis?
radioactive iodine uptake scan
what happens in exophthalmos? Which disease is it associated with?
an antibody binds to muscles behind the eye and stimulates growth factor receptors causing them to bulge, graves disease
pretibial myxoedema (swelling of shins) is associated with?
graves disease
what type of goitre is caused by graves disease?
smooth goitre
what type of goitre is caused by Plummer’s disease?
toxic nodular goitre
How does Plummer’s disease work?
benign adenoma that is overactive making thyroxine
What does excess thyroxine do to the sympathetic nervous system?
sensitises beta adrenoreceptors to ambient levels of adrenaline and noradrenaline
what are 5 symptoms of hyperthyroidism?
weight loss increased appetite heat intolerance diarrhoea lid-lag
what causes lid-lag in hyperthyroidism?
excess T3 makes adrenaline hold eyelids back
propyl-thio uracil and carbimazole are which type of drug?
thionamides (anti-thyroid)
how do the thionamides work?
block thyroid peroxidase and prevent synthesis of T3/T4
how does potassium iodide work?
used in preparation of hyperthyroid patients for surgery and turns everything off for 10 days because of iodine overload
how does radioiodine work?
goes into thyroid and destroys it
name 2 side effetcs of thionamides
agranulocytosis (reduction in neutrophils), rashes
What are 5 symptoms of thyroid storm?
- hyperpyrexia > 41 degrees
- accelerated tachycardia/ arrythmia
- cardiac failure
- delirium / frank psychosis
- hepatocellular dysfunction; jaundice
how many of the 5 symptoms for thyroid storm must be present for diagnosis?
2
what is the follow up for thionamide treatment?
Follow up after 18 months, maybe try them longer if not working –> surgery/ radioidine
state 3 risks of thyroidectomy
voice change, losing parathyroid glands, anaesthetic
what are beta blockers used for?
control of symptoms while waiting for thionamides to work
how would viral thyroiditis present in a radioiodine scan?
no iodine uptake - nothing
painful dysphagia, hyperthyroidism, pyrexia and thyroid inflammation are a sign of?
viral thyroiditis
what is the presentation of viral thyroiditis?
1 month hyperthyroidism, 1 month hypothyroidism, then normal again
why do viral thyroiditis patients have hyperthyroidism during the first month?
thyroid cells damaged and release lots of stored thyroxine
A 30 year old woman attends clinic and presents you with a letter from a private health clinic. She has been experiencing palpitations. The letter contains the following results:
fT4 30 pmol/L (9 - 23)
fT3 11 pmol/L (3.1 – 6.8)
TSH <0.01 mU/L (0.3 – 4.2)
what’s the diagnosis?
primary hyperthyroidism
what conditions can cause primary hyperthyroidism?
- graves - autoimmune
- plummer’s disease - toxic multi-nodular goitre or a singe adenoma/ hot nodule
- Inflammation of the thyroid - post-partum or viral
- Drug-induced
On examination a patient with primary hyperparathyroidism had a fine tremor and looked thin. Her pulse was 112 beats per minute and her blood pressure 106 / 70 mmHg. Examining her neck, there was a mass in the centre of her neck, which was soft, extended symmetrically either side of the midline and was not tender to touch. This mass moved with swallowing. She had bilateral exophthalmos (prominent eyes).
What’s the diagnosis? Why?
grave’s disease
exopththalmos and smooth, symmetrical goitre
What investigation could be used to confirm the cause of her hyperthyroidism?
Anti-TSH receptor antibody test
Radioactive iodine scan
what is the first line of treatment for hyperthyroidism?
beta blockers and thionamides
what is potassium iodide used for? How does it work and for how long?
preparation of hyperthyroid patients for surgery, turns everything off for 10 days due to iodine overload
also used in severe thyrotoxic crisis
after 18 months of thionamides, what should the doctor do?
- prescribe further thionamides and monitor
2. Radioiodine OR thyroidectomy
give two examples of thionamides
propyl-thio uracil
carbimazole
what precaution should you take if taking radioiodine?
avoid people for several days
