Cushing syndrome @phloston and other people

[doc0610]

I was recently doing u world and had a doubt regarding this.

1) cushing syndrome would cause HTN hence would cause dec in PRA and aldo concentration. Which is perfect
But, in question 40091492 it said that there is an inc in aldo. Which is not the case as aldo isn't dependent on ACTH, right? also how are deoxycorticosterone and corticosterone dependent on ACTH when they are the precursors for Aldo?

2) Also in a question with Hypertension and hypokalemia the diffrential is cushing syndrom but the PRA and aldo is less.

any inputs?

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[Phloston]

I was recently doing u world and had a doubt regarding this.

1) cushing syndrome would cause HTN hence would cause dec in PRA and aldo concentration. Which is perfect
But, in question 40091492 it said that there is an inc in aldo. Which is not the case as aldo isn't dependent on ACTH, right? also how are deoxycorticosterone and corticosterone dependent on ACTH when they are the precursors for Aldo?

2) Also in a question with Hypertension and hypokalemia the diffrential is cushing syndrom but the PRA and aldo is less.

any inputs?

1) I'm not 100% sure what your specific question is, but Cushing causes HTN because cortisol increases expression of alpha-1 receptors on arterioles, thereby allowing catecholamines (e.g., NE, E) to agonize them; this is called a permissive (not additive or synergistic) effect that cortisol has on catecholamines. Cortisol also has mineralocorticoid effects (although not as significant as aldosterone) that lead to increased Na+ reabsorption in the principal cells of the cortical collecting duct. Therefore one could posit that lesser aldosterone concentrations would be needed if cortisol is high, but the mechanism is a bit of a stretch. Aldosterone is not dependent on ACTH. The precursors, corticosterone and 11-deoxycorticosterone, aren't dependent on ACTH either as far as I'm aware.

2) As per above, cortisol has mineralocorticoid effects, so HTN + hypoK are possible. This would decrease the need for aldosterone. But I'd say aldosterone doesn't have to be decreased in Cushing. Bottom line is I wouldn't over-think things in terms of compensatory aldosterone changes in relation to Cushing. On the USMLE, just be reasonable with respect to what information the vignette provides and let that guide you to your answer.

 

[doc0610]

So, the questions was regarding secondary hypertension. Now, cushing syndrome does cause htn, which i get, but, it said the deoxycorticosterone and cortocosterone and cortisol which are ACTH dependednt and cause it via vasoconcentration. Hence, my doubt.

 

[Phloston]

So, the questions was regarding secondary hypertension. Now, cushing syndrome does cause htn, which i get, but, it said the deoxycorticosterone and cortocosterone and cortisol which are ACTH dependednt and cause it via vasoconcentration. Hence, my doubt.

The precursors of aldosterone, 11-deoxycorticosterone and corticosterone, are in the zona glomerulosa. ACTH acts at the fasciculata and reticularis.