Treating excessive steroids with steroids!

[kenlee]

12 year old boy has Autosomal Dominant disease with Ectopic overexpression aldosterone synthase
lab: increased 18-oxocortisol, increased 18 hydroxycortisol
whats the treatment?
a. candesartan
b. Dexamethasone
c. mannitol

ans: B
what is this disease and why do you give steroid if there is already high steroid?

[haga]

This question has nothing to do with clinically relevant disease, they are testing whether you know about aldosterone production.

If you look at the aldosterone prod. pathway....the last step is conversion of corticosterone to aldosterone by aldosterone pathway. So basically what you have to do is decrease corticosterone production. The way to do this is to decrease ACTH as this is the signal to produce corticosterone.

Giving dexamethasone will suppress ACTH which will cause decreased corticosterone production. So even though aldosterone synthase levels can stay high it won't matter cuz there will be nothing to convert.

[Dr.NickRiviera]

Originally Posted by haga

This question has nothing to do with clinically relevant disease, they are testing whether you know about aldosterone production.

If you look at the aldosterone prod. pathway....the last step is conversion of corticosterone to aldosterone by aldosterone pathway. So basically what you have to do is decrease corticosterone production. The way to do this is to decrease ACTH as this is the signal to produce corticosterone.

Giving dexamethasone will suppress ACTH which will cause decreased corticosterone production. So even though aldosterone synthase levels can stay high it won't matter cuz there will be nothing to convert.

isn;t it true though that high dose dexamethasone does NOT decrease ectopic secretion of ACTH? in fact, thats the test by which we determine ectopic release vs release from pituitary in hypercortisolism, no?

[kenlee]

Originally Posted by Dr.NickRiviera

isn;t it true though that high dose dexamethasone does NOT decrease ectopic secretion of ACTH? in fact, thats the test by which we determine ectopic release vs release from pituitary in hypercortisolism, no?

its not ectopic ACTH secretion
it was ectopic aldosterone synthase overexpression

[Dr.NickRiviera]

Originally Posted by kenlee

its not ectopic ACTH secretion
it was ectopic aldosterone synthase overexpression

what reaction exactly does aldosterone synthase catalyze?