Cushing Syndrom

[uchicago]

Got a q:

If a pt w/ abn 24h urinary cortisol, no response to high dexamethazone suppresion test and high ACTH. What is the Dx??

I know if 24hr unrary corisol is positive=cushing
no response to dexa supp test= r/o pit adenoma
you left with lung and adrenal but high ACTH goes with lung ca or any paraneoplastic synd, right? I found the answer is Adrenal ?? can someone please explain this for me? Plus, you do NOT have other lab w/ adrenal cause; high DEAS, high 17-KS.

Thanks

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[AndyRSC]

The results suggest lung cancer. Because an adrenal tumor would be likely to secrete cortisol itself, rather than ACTH, the high ACTH points to lung.

 

[uchicago]

The results suggest lung cancer. Because an adrenal tumor would be likely to secrete cortisol itself, rather than ACTH, the high ACTH points to lung.

that's what i thought

 

[OveractiveBrain]

Got a q:

If a pt w/ abn 24h urinary cortisol, no response to high dexamethazone suppresion test and high ACTH. What is the Dx??

I know if 24hr unrary corisol is positive=cushing
no response to dexa supp test= r/o pit adenoma
you left with lung and adrenal but high ACTH goes with lung ca or any paraneoplastic synd, right? I found the answer is Adrenal ?? can someone please explain this for me? Plus, you do NOT have other lab w/ adrenal cause; high DEAS, high 17-KS.

Thanks

24-hr urine elevated = cushing's syndrome... great, now its Lung, Pitutary, Adrenal, or Iatrogenic
ACTH elevated = driven by pitutary or ectopic... as soon as teh ACTH is elevated, it ELIMINATES adrenals
High Dose Fails to suppress = NOT the pituitary

therefore... Its ectopic, most likely source is lung cancer (small cell)

there is a whole lecture about it (endo--> adrenal):

www.onlinemeded.org