I just got my dexamethasone suppression test results back. My cortisol was very low which indicates to me a normal result of the test. I don’t take any steroids so I’m not sure why there was an initial discrepancy between my ACTH and cortisol levels.
Thank you and I am glad to hear that your Dex Test came back normal. And your result should truly be considered accurate since you do not take any steroids. I would think this means (in your case) that your adrenals are not producing Cortisol independently of the HPA axis and it rules out an adrenal tumor or adrenal Cushing's. Is this how your doctor interpreted your results?
I did not enjoy that test, at all. In the first half hour after taking the dexamethasone, I felt great. My muscle pain faded away and my brain fog cleared significantly. But that faded and I became irritable, itchy, restless, and couldn’t sleep at all. I already struggle with insomnia and throwing all of that on top of it meant I didn’t get any sleep. I am very sensitive to medications so you may not have the same experience.
I had an absolutely horrific experience the two instances in my life that I took dexamethasone in 2016. I honestly would never want to take it again although I'd consider it for this test if both my doctors feel that I need to do it. I am not surprised at all that you did not get any sleep. Did it also cause you to have severe tachycardia, agitation, confusion, or other abnormal neurological symptoms?
However, if your ACTH is already undetectable then I’m not sure why your doctor would order the suppression test. Dexamethasone lowers ACTH, which should normally lower cortisol. If your ACTH is already undetectable then I don’t think your test results would mean anything.
This is actually my thoughts exactly! Although there must be a way that Dex suppresses ACTH that is different from how Cortef/HC suppresses it (or it must affect Cortisol production in some other way)? Otherwise, I also do not understand what new info this test would provide? And I would not be taking any hydrocortisone during this test, only the Dex, in case that is relevant? But I am honestly hoping that I will not need to do it at all!
I’m not a doctor but it sound to me like a pituitary issue and not an adrenal one. Undetectable ACTH means your pituitary isn’t producing it. Normally, this would mean undetectable cortisol, as well. It sounds to me like the cortisol tests are detecting your Cortef and not endogenous cortisol, especially given that you are a slow metabolizer.
That was my feeling, too. I feel that it is possible that the Cortef/HC that I am taking (even though it is a low dose) has suppressed my pituitary and even when I was finally completely off the Cortef (following a 2+ year taper), my pituitary was not able to kick back into gear and start creating ACTH on it's own. I have heard of cases where this process (with the pituitary and the HPA axis) can take months to start producing ACTH again.
I wish that I could have waited it out (to see if this was the case for me) but I started to have the signs of an adrenal crisis and both my ACTH & Cortisol were basically undetectable at that time (although my Cortisol was not completely undetectable, just VERY low). I also was barely able to function and it made me very ill so my doctor said that I had to go back onto the Cortef (HC) which I did. This was approximately one year ago.
I suspect that now my pituitary is still completely suppressed (probably from the HC plus potential inflammation or autoimmunity) so it is not creating ACTH and that the Cortisol that is showing up on the blood test is from the Cortef pill and is not endogenous Cortisol b/c I am a slow metabolizer (exactly like you said). This is what makes the most sense to me vs. that I have an adrenal tumor or adrenal Cushing's (plus I do not have the symptoms that would match with that).
I would ask if there would be a benefit for an brain MRI without contrast.
My understanding is that there really would not be a benefit without contrast (unless I had a brain tumor but neither of my doctors think that)! To see pituitary inflammation, you would need contrast dye, and it is possible that even WITH contrast, the inflammation would be so small that you would not see it. Also my endocrinologist is now focused on my adrenals vs. pituitary (but he said that this is just a theory and we'd need to test it out to confirm it).
I would actually love to be tested for autoantibodies that attack the pituitary but there is no commercial test for this.
If you are unable to stop taking Cortef before a cortisol test, you might ask your doctor about temporarily increasing your dose of Cortef (if you are able) before a cortisol test to see if your cortisol level increases while ACTH remains undetectable. That could indicate it’s the Cortef showing up on your cortisol tests.
I am able to stop it for 24-hours but not much longer than that (and I will not feel well during that period). What you just recommended makes sense but in my case, it doesn't turn out to be true. We monitored my ACTH & Cortisol every 3-4 months during the 2+ years that I was doing the taper off Cortef (HC) through the present and I created a chart for my doctors with all of the lab results and they don't correlate in the way that you described (meaning that me taking a higher dose of Cortef/HC does not equal a higher Cortisol level on a morning blood test).
On University of Michigan's website:
"A problem with the adrenal glands or pituitary gland. A high level of ACTH and a low level of cortisol (or low ACTH and high cortisol levels) could be caused by a problem with the adrenal glands. Low levels of ACTH and cortisol could be caused by a problem with the pituitary gland."
This also makes total sense to me. In my case, I have a VERY low (undetectable) ACTH level and a lowish (but in the normal range) Cortisol level. To me this would fit with a pituitary problem but my endocrinologist is now thinking that since the Cortisol is not undetectable (and it is within the "normal" range), that it is an adrenal problem.
) but just in case it is useful, my ACTH on blood tests is below the range where it is flagged as too low and it can only be labeled as "undetectable". At Quest (lab) in the US, anything < 5 for ACTH is labeled as undetectable.