EN8

Question 1

what are the three areas of adrenal cortex

Answer 1

zona fasciculata: cortisol
zona reticularis: sex steroid
zona glomerulosa: aldosterone (controlled by renin)

Question 2

what are the 4 syndromes of adrenal insufficiency?

Answer 2

primary
secondary
acute adrenal insufficiency
congenital adrenal hyperplasia

Question 3

what are the stimuli of aldosterone production

Answer 3

hyperkalaemia
hyponatraemia
beta-1 adrenoceptor stimulation
drop in renal blood flow

Question 4

what is the main function of aldosterone

Answer 4

promotes Na in K out

salt balance

Question 5

what are the differences between GR and MR

Answer 5

GR: wide distribution, selective for glucocorticoid, low affinity for cortisol

MR: discrete distribution (mainly in kidneys), doesn’t distinguish between aldosterone and cortisol, high affinity for cortisol

Question 6

name the enzyme that inactivate cortisol

Answer 6

11beta hydroxysteroid dehydrogenase 2

Question 7

what are the glucocorticoid substitutes and how they differ

Answer 7

hydrocortisone: only bind MR at high dose, 8hr duration
prednisolone: only bind MR very weakly, 12hr duration
dexamthasone: doesn’t bind MR at all, 40hr duration

Question 8

what is aldosterone substitute

Answer 8

fludrocortisone

Question 9

what two drugs can be taken parenterally

Answer 9

hydrocortisone

dexamethasone

Question 10

describe the distribution of the drugs

Answer 10

hydrocortisone binds 90-95% to CBG
Prednisolone less bound
Dexamethasone even less bound
fludrocortisone only binds to albumin not CBG

Question 11

what is the precursor to check for congenital adrenal hyperplasia when it is 21 hydroxylase deficiency

Answer 11

17 hydroxyprogesterone

Question 12

why does the dosage of glucocorticoid increase when body is stressed

Answer 12

cortisol is needed by the body to recover from illness. Body naturally produce more cortisol during stress (e.g illnesses or general anaesthesia)
In patients who can’t produce cortisol naturally on their own, lack of cortisol means they are more prone to infection and less likely to recover. They therefore have to double the dosages to mimic the physiology.

Question 13

what is the difference between normal cortisol production and stressed cortisol production

Answer 13

normal: 20mg/day
stress: 200-300mg/day