I don't have Cushing's but it's a long story how my cortisol values were at the upper end of normal. (More later.)
I've become more bedbound lately and haven't left my home since Nov. 2017. I developed severe shortness of that came on over a period of about 2 weeks and I had an episode of severe chest pain that lasted several minutes and sudden pedal edema. I'm not well enough to leave my home and have it thoroughly evaluated although I was able to get a chest x-ray and EKG at my very last visit. It could be a pulmonary embolism just based on my Google skills and other symptoms. I've had some home visits from my HMO (Kaiser doctor) but they can't do echocardiograms or pulmonary tests at home. My O2 levels fall just when walking from one room to another and the doctor saw this on his oximeter which exactly matched my own oximeter when read at the same time.
Regarding the elevated cortisol values: I started taking spironolactone in May 2014, then in Sept. 2016 my PCP wanted me to discontinue it since it could "alter my chemistry" which was vague but I thought he was more or less thinking of potassium and HbA1c elevation. I had been taking it for fibromyalgia pain and elevated blood pressure.
In Jan. 2017 I was diagnosed with hypothyroidism and began taking Cytomel and Armour. We battled about doses and whether I really needed to be on it. He infuriated me so much that I changed doctors.
I started taking spironolactone again in June 2017 under a new doctor who didn't want me restarting it on my own but I explained how it helped some symptoms, etc. Some time after that I read that spironolactone could elevate cortisol. Having a cortisol level that is too high or too low will interfere with T4 to T3 conversion and it will also interfere with the entry of T3 into the cell. I asked my new doctor if he could switch me to eplerenone, similar to spironolactone, except that it will not alter cortisol. He said that he had no experience with it so I just left things as they were.
Eventually I'd had enough fooling around with thyroid meds, blood tests, etc. I asked my doctor again about eplerenone. He still had no experience with it but I pressed him to talk to a pharmacist to get advice on converting doses. By the end of May 2019 I was off spironolactone and on eplerenone. By mid-July 2019 (45 days later) I was having symptoms of hyperthyroidism such as spontaneous sweating and either elevated BP or heart rate (can't remember which now). I tapered off all thyroid meds, had my last thyroid blood test in September which was normal.
My doctor did give me the credit for asking to discontinue spironolactone. Hooray! The second thing that may have helped my thyroid was raising my ferritin level. It was 22 to 55 (low normal) February 2016 to March 2019, then 84 (much better) in November 2019.
I'd like to have thyroid tests again soon. The two symptoms that I have when I'm hypothyroid are lack of peristalsis (no movement after a meal) and dry itchy skin. These are so-so right now but they've been a lot worse.
The other thing that was affecting my TSH result was quetiapine. TSH can fail to elevate in the presence of hypothyroidism and quetiapine can cause hypothyroidism. I had thought quetiapine was causing the thyroid problem at first because I started taking it in May 2015 and it can sometimes take up to four years for hypothyroidism to take place. I'm still taking the same dose of quetiapine. When I was getting tested (TSH, freeT4) I had to keep reminding my doctor that the TSH while taking quetiapine could be suppressed - it's even in the package insert. I was also taking T3 which suppresses free T4. Eventually we got my TSH between 1 and 2 which is where I felt best.
If I ever have to go back on thyroid meds I'll choose levothyroxine (Synthroid - synthetic T4). At least that way I can see what a free T4 value would look like without dealing with it being suppressed by anything with T3 in it like Cytomel or Armour. In Feb. 2019 I stopped Armour and started levothyroxine but stayed on Cytomel. I was in the process of lowering my dose of Cytomel and raising levothyroxine when I stopped them altogether in July 2019. Staying off anything with T3 in it would be important to me because I'd like to see what an unsuppressed free T4 value would look like and that may not be important for anyone who is not taking quetiapine (TSH can fail to elevate in the presence of hypothyroidism).