Cushing disease vs syndrome

[kderekb]

I understand the difference between cushing disease and syndrome.
Here is my question.

Cushing disease causes excess ACTH, which stimulates the zona fasiculata (excess cortisol) and zona reticularis (excess androgens) and therefore can cause amennorhea/hirsutism and everything associated with excess androgens and cortisol(symptoms not mentioned).

Cushing syndrome can be caused by exogenous corticosteroids or by adrenal hyperplasia/adenoma/carcinoma. This leads to excess cortisol (just like Cushing disease), but why does this cause amennorhea/hirsutism? Nothing is stimulating the sex steroids, and negative feedback should be slowing or stopping any ACTH. Am I missing something? In my opinion, cushing syndrome should have no effect on the sex steroids because there is no excess of ACTH stimulating the zona reticularis, but everywhere I read it mentions hirsutism/amennorhea/loss of libido for both Cushing's syndrome and disease.

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[Postictal Raiden]

In the case of adneoma, you get an increase of hormone productions from all three layers. Also remember that cortisol and androgen aren't only produced by the fasiculata and the reticularis layers respectively, some of each is also produced by the other layer.

In the case of the exogenous cause, I don't have an answer.

 

[hallowmann]

Ectopic cushings could be (and classically for exams is) a paraneoplastic syndrome like SCLC producing ACTH. Because it is not normal pituitary tissue (its lung), it doesn't respond to the negative feedback cascade associated with excess cortisol. In other words its unaffected by control mechanisms because it's already making ACTH abnormally. This is why you can differentiate between ectopic ACTH vs. pituitary adenoma with high dose suppression (ectopic won't suppress).

 

[zedssssssss]

easy way to remeber it...D (head) is above S (adrenals)