Hyperthyroidism Flashcards
hypothalamus hormone regulating TSH secretion:
trh
autoimmune hyperthyroidism cause
graves’ disease. antibodies vs TSH receptor in thyroid. primary hyperthyroidism
Graves’ disease symptoms
smooth goitre, tachycardia/palpitations, intolerance to heat, muscle spasms, weight loss and increased appetite, diarrhoea, exophthalmos, pretibial myxoedema (last 2 are specific to graves’)
Radioiodine uptake in graves
Uniformly high
why does exophthalmos occur
same antibodies bind to receptors in the eye muscles
what are toxic nodules
benign adenomas that cause localised hyperthyroidism
radioiodine uptake for toxic nodules
localised hot spots of activity since nodules are overactive in producing thyroxine
how does thyroxine affect the sympathetic nervous system
sensitises beta-receptors to background levels of (nor)adrenaline, so there are sympathetic symptoms in hyperthyroidism such as muscle tremors and tachycardia
what is thyroid storm
medical emergency of high thyroid activity
signs and symptoms:if thyroid storm
hyperpyrexia above 41°C, tachycardia, delirium/psychosis, cardiac failure, hepatocellular dysfunction → jaundice
what drugs are used to treat hyperthyroidism
thionamides e.g. propylthiouracil & carbimazole, potassium iodide KI, radioiodine, beta blockers(given to treat sympathetic symptoms)
thionamides mechanism of action?
lower thyroxine production by inhibiting thyroid peroxidase
Given as and 18 month course with treatment expected to stop after (half are cured half relapse) if not cured consider surgery radioiodine or lifetime treatments with carbimazole
thionamides side effects?
agranulocytosis - usually reversible reduction in neutrophils, rashes
what does KI do and when is it used
inhibits thyroglobulin iodination, inhibits H2O2 generation and thyroid peroxidase. used for thyroid storm, hyperthyroid patient surgery prep. not regular graves’ treatment
wolf chaikoff affect
Reduces symptoms in 1/2 days and given for 10 days usually, if any longer there may be escape and thyroid hormones might be made
Vascularitt and size of gland reduces in 10-14 days
risks of thyroid surgery
anaesthetic risks, risk of voice change, scarring, risk of parathyroid gland loss
radioiodine contraindications:
pregnancy. have to stay away from pregnant women and young children for a few days after taking.
what is de quervain’s thyroiditis?
Viral thyroiditis
de quervain’s symptoms?
painful dysphagia, pyrexia, thyroid inflammation,malaise and pain radiating to ear
thyroid activity pattern during de quervain’s
thyroid stops making thyroxine and makes virus instead, thyroxine stores used. hyperthyroid for a month then stores depleted so hypothyroid until resolution about a month later.
radioiodine uptake in de quervain’s
zero since no thyroxine is being made so no iodine is taken up
postpartum thyroiditis cause and symptoms
immune system modified in pregnancy leading to similar symptoms but no pain.
How does TSH work extra
TSH binds to TSH receptor on follicular cell causing active transport of iodide ions into follicular cells via sodium iodide symporter
Iodide ions are oxidised to iodine
TSH binding causes thyroglobulin production and hydrogen peroxide and thyroid peroxidase
Iodine added to thyroglobulin to make MIT DIT
B blockers use in thyrotoxicoses
Several weeks for ATDs to have clinical effects eg reduced tremor and slower heart rate and less anxiety
Non selective eg b1 b2 eg propanolol
