EN 4 Flashcards
what are the causes of hypothyroidism
autoimmune damage
tumour
clinical features of hypothyroidism?
fatigue, depression, constipation, deepen voice, cold intolerance, weight gain with loss of appetite, bradycardia, myxoedema coma, hypertension, enlarged heart
How does T4 convert to T3
T4 is a prohormone
T4 undergoes deiodination by deiodinase enzyme which turns into a more biologically active T3
how does thyroid hormone work in cell?
Both T3 and T4 get picked up and enter the cell.
In the cell T4 is converted into T3 ==> T3 binds to trimer of RXR+TR+TRE ==> alter gene expression
How are T4 and T3 called in thyroid hormone replacement therapy?
T4: levothyroxine sodium
T3: liothyronine sodium
what’s the difference of primary and secondary hypothyroidism?
primary: autoimmune ==> endocrine gland itself wrong
secondary: pituitary gland wrong
what’s clinical use of levothyroxine?
oral
TSH is used as guidance
Under what circumstances will primary hypothyrodisim happen?
post thyroidectomy
post radioactive iodine
under what circumstances will secondary hypothyroidism happen?
post pituitary surgery
radiotherapy
(use fT4 as guidance)
when do you use T3
myxoedema coma
what’s the half life of t3 and t4
t3: 2.5 days
t4: 6 days
