HYPERTHYROIDISM Flashcards
where is thyroxine stored
in thyroglobulin in thyroid follicular cells
what is the full name of T4
THYROXINE
FULL NAME of t3
triiodothyronine
how much thyroxine is approx stored in your thyroid any given moment (how long would you last with it)
1 month worth
how does the pituitary help thyroxine formation
1) increases iodine uptake and oxidises it to inorganic
2) stimulates tsh
what does TSH do exactly
goes down to thyroid follicular cells activates enzymes that trigger the release of stored thyroxine (t4) into blood
where does t4 provide negative feedback?
pituitry AND hypothalamus
thyroid related hormone released by hypothalamus and on what cells does it act
thyrotropin releasing hormone on thyrotrophs in anterior pit
what happens to TSH levels when autoimmune hypothyroidism?
tsh goes up
is graves disease autoimmune
hyper or hypothyroididsm
hyper
mechanism of graves
TSH- receptor antibodies (TRAb) bind to and stimulate TSH receptor in thyroid
symptoms of graves (ones i remember easily)
everything hyeprworking so:
visual:
- lid lag
-exophtalmos- cubbed fingers in severe exophtalmos cases
tempeprature and gastro:
- hot, flushing, hungry, eating more but losing weight, diarrhea
other graves symptoms (ACRONYM: HERE) (harder)
HEART+ respiration: rapid pulse, palpitation, tachycarida, breathless
EMOTIONAL: nervousness excitsbiluty, restlessness, emotional instability, insomnia
REPROD: oligomenorrhea or amenorrhea
EXTERNAL: observable in appearance: localized myxedema, tremor, muscular weakness
Mechanism of exophtalmos
antibodies bind to muscle behind the eyes
what is pretibial myxoedema
non pitting oedema (you cant squish it in) in the shins in graves disease
what does myxoedema refer to?
hypothyroidism
what is the first line investigation to confirm graves disease
measuring TRABin blood
what happens to the thyroid in graves disease
diffuse (omiomorfo) enlargement ( smooth goitre) and engorgement (bleeds very easily)
how does graves disease thyroid look in radiology scan after giving radioiodine?
whole thing “lights up” in black
does toxic nodular disease lead to hyper or hypothyroidism
hyperthyroidism
2 categories of toxic nodular disease
single toxic nodul or multiple toxic nodules (multinodular goitre)
what is the mechanism behind toxic nodular disease
benign adenomas that are overactive at making thyroxine
how does toxic nodule disease look in radiology scan after giving radioiodine?
only hot nodule lights up in black
by what mechanism does thyroxine act on the sympathetic nervous system?
sensitizes beta adrneoreceptors to ambient (surrounding) adrenaline and noradrenaline so activates symp nervous system
what are the symptoms caused by the activation of the symp nervys system by thyroxine?
tachycardia, palpitations, tremor in hands, lid lag
what is a thyroid storm, how do you react if you catch it?
when you are so hyperthyroid that it turns into a medical emergency, 50% mortality if untreated, treat it QUICKLY
what are the alarm symptoms of htyroid storm? (if u have 2 ur at high risk)
- hyperpyrexia >41 degrees celcsius
- accelerated tachycardia / arrhythmia (arr. is the advanced version of tachy)
- cardiac failure
- delirium
- hepatocellular dysfunction / jaundice
what are the treatment options for hyperthyroidism
surgery
drugs
radioiodine
what are the categories of drugs use to treat hyper?
radioiodine
thionamides
potassium iodide
b blockers
two options of thionamides
PTU - propylthiouracil
carbimazole (CBZ)
what type of enzymes are the ones involved in the formation of thyroxine?
peroxidases
what do peroxydases do?
they peroxydase iodine to form monoiodotYROSINE and DIT ect
how do thionamides work
inhibit peroxydases
do thionamides work for graves and toxic nodules?
yes
how often do you need to take thionamides
daily
when will thionamides start showing effects on patient?
weeks later because stored thyroxin needs to be used up first
when is the biochemical effect of thionamides observed after administration?
immediately
what will you give patients for short term relief
b- blockers - dont actually fix the problem only the symptoms - palpitaitons ect (its nervous system related)
what type of b blocker do you need to give ( and give example of 1 specific drug)
NON selective b blocker ex. propanolol (bc the re are also some more advanced versions that are selective for heart)
what is a risk of taking thionamides?
1/10,000 people will develop agranulocytosis: reduction of neutrophils: immunosupression very dangerous
signs of agranulocytosis
sore throat and rashes
management of agranulocytosis?
1)withdrawal of thionamides,
2)go to hospital, full blood count, if no white cells u go into side room bc u have no immune system
3) if sore throat give broad spectrum antibiotics
4) give you drugs to wake up your immune syst
how long do you need to follow up with antithyroid drugs?
18 months
what happens/ what do you do after 18 months of antithyroid treatmnet
you review patient periodically with thyroid function test: 50 % patients recover 50% relapse
what do you do if they relapse?
surgery
radioiodine
or if they dont wnat hose lifetime carbinozole
in what cases should you use iodine
1) before surgery
2) emergency treatment of thyroid storm
because it shuts down thyroid gland within 1-2 days
as part of what compound do you usually give iodine
KI
how do we think that Iodine works? (not been proven)
inhibition of thyroid hormone synthesis and secretion
1) inhibits iodination of thyroglobulin
2) inhibits H2O2 generation + thyroperoxidase
when should you not give iodine
as a long term treatment option of graves disease because it stops having an effect after 10 days
why iodine good for surgery
makes it smaller and less likely to bleed in surg within 10-14 days
stops tachycardia: also good for surg: better anesthesia
possible side effects of surgery
risk of voice change
risk of parathyroid gland damage ( bad for bones ect)
scar
aneasthetic related risk s
what are the two types of radioiodine you can give and for what 2 purposes
1) iodine 131 as a TREATMENT
2) iodine 99 Tc (pertechnetate) only for scans not as treatment
what is the thing that should be considered when takinf radioiodine?
its radioactive, prgenanct moms shouldnr and also you need to avoid moms and chldren if ur taking it bc ur radioactive
what is the best treatment rn according to NICE?
radioiodine
what is a unique symptom of viral thyroiditis
neck pain
what happens to stored thyroxine during the first month of viral thyroiditis?
it all gets used up
why does all the stored thyroxine get used up?
because the virus prevents you from making any new thyroxine
what does this mean for iodine uptake and scan images in viral thyroiditis?
NO IODINE uptake bc no new thyroxine synthesized and nothing lights up as black in scans
what are the levels of TSH and Thyroxine in first month of viral thyroiditis?
t4 elevated tsh low
what hapens to your blood thyroxine levels during the second month of viral thyroiditis and why
t4 levels fall below normal (hypothyroid) because all the stored thyroxine has been used and new thyroxine is still not made sufficiently
how long after viral thyroiditis is slow recovery observed?
3 months
what is postpartum thyroiditis ?
similar to viral but 1) no neck pain 2) is after pregnancy
why does postpartum thyroiditis happen?
bc immune system is supressed during pregnancy and as it gets unsupressed after preg, thyroid gland becomes inflamed.
