Hi everyone um today we’ll be talking about dextrometers on suppression tests and um this is going to be just a very simplified version to understand how it works and obviously the indication for this kind of test is when you suspect any sort of cushing’s disease or syndrome going on with the patient if you have a patient presenting with hypertension diabetes
Truncal obesity moon phases abdominis tria and etc then you might be suspecting cushing’s disease so or cushing’s syndrome if you see the signs and symptoms of cushing’s the first thing you want to do is actually to do a low dose dixa suppression tests test not um two only one test so this tests thinking about it if you still have cortisol being elevated
That means you fail to suppress the release of cortisol so that means that there is pathological release of this cortisol so if you fail to suppress then you have an element or you might be having higher suspicion of cushing’s okay other alternatives for the low-dose dexa medicine suppression test is to get your 24 hour cortisol levels or sometimes you want
To get salivary cortisol levels okay now what you need to know after that is whether the cortisol release is dependent on actu if you look at this graph we know physiologically that cortisol is under the influence of acti so if the abnormal amount of cortisol is being secreted from or being influenced by acti then that would be different from if the adrenal
Gland is releasing action its own and we know cortisol exhibits a negative feedback on the whole axis so we can easily just obtain levels of acti right and if it’s high it’s going to mean something and if it’s slow it’s going to mean something if it’s slow then you have a problem here you have a tumor or an adenoma or any kind of neoplasm that is excessively
Releasing cortisol and then it’s exhibit it’s exhibiting a feedback negative feedback on the um both the hypothalamus and adrenal gland so it’s non-acth dependent type of release so you might be thinking of primary adrenal tumor and of course to evaluate for this you want to get ct or mri okay but then what if the actu is high so the release of cortisol is
Actually dependent on the axis itself then you want to know if this is a malignant release of action or if this is a non-malignant release of acth so this this is where the high dose the examination suppression test comes into play and in that case you we want to know does does it respond to the high dose or does it not respond if it responds that means it’s a
Benign type of release because high dose dexamethasone should be able to suppress cortisol if it’s benign in nature so you would be thinking most likely cushing’s disease where you have pituitary adenoma there and it’s the ones creating acti which subsequently is secreting cortisol so with high dose suppression you are able to shut off the access again this is
Not malignant it’s an adenoma so cushing’s disease and this is most likely likely due to a pituitary adenoma obviously in that case you obtain mri and then you consider options of treatment whether you want to remove it the adenoma through transphenol surgery whether you want to use um management options for the patient but the thing is if it does not suppress
Um even with high dose dexamethasone then that’s an ectopic release of acth so ectopic act release and that is worrisome of certain cancers such as small cell carcinoma of the lungs sometimes peridoplastic syndrome usually is the word we use to talk about humors that releases hormones which are functioning so you want to do ct scan and explore the cause or the
Location of the tumor causing the ectopic release of aceth so in summary this test is used to determine two things first of all whether we do have abnormal release of cortisol or not and we obtained that through the low dose dexamethasone suppression test and then we want to know is this act h dependent or not if it’s not dependent and that’s that’s solitary
Release of cortisol from the adrenal gland itself that allows for shutting of the axis through normal negative feedback so that is seen in primary adrenal tumors but if you have high act h then that means that there is an influence of a higher axis whether it’s by tumor ectopically which does not respond to high dose suppression because it’s malignant it’s out
Of control or it might be an adenoma that releases acti and therefore cortisol and since it’s an adenoma it’s benign it does respond to high dose dexa medicine separation test so this is basically in a nutshell um how to think about um dexter medicine suppression tests and yeah and if you go again look at the physiology everything makes sense so hope this was
Clear and thank you very much for watching
Transcribed from video
Dexamethasone suppression test made easy. Cushing's work up By Medicine in easy font
