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misseili
This patient has Cushing Syndrome and as you stated their feedback inhibition is hampered. Low-dose dexamethasone causes a decrease in cortisol in normal individuals but not in those with Cushing Syndrome, only high dose dexamethasone causes a decrease in cortisol with Cushing Syndrome. Add'l info: In ectopic ACTH (ie Small cell lung cancer) high dose dexamethasone leads to no change in cortisol. Pathoma 2020 Pg 171
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submitted by โepiglotitties(29)
I understand that feedback inhibition isn't working and is why ACTH is undetectable/low (and why there is no change after dexamethasone), but wouldn't cortisol levels increase after dexamethasone? Or does dexamethasone not count as cortisol when quantifying serum levels? pls help