In Addison's Disease, the cortisol production by our adrenal glands is too low. Cushing's syndrome is where there's excessive corticosteroid--usually from being on higher doses of steroids. In medicine, we typically call it Cushing's Disease only when the excess cortisol results from a pituitary tumor stimulating the adrenals to produce too much. And you're right--around 5-7 mg daily steroids is roughly physiologic, i.e., what our bodies normally produce on a daily basis. It's when we get below that level that our adrenal gland starts to function more again, and it can take time for it to recover.

Do you want to talk with your rheum about the possibility of weaning the steroids? That's the best way to treat Cushing's syndrome from steroid use. Perhaps they might want to consider an immunosuppressant instead? That's the usual path in the U.S., as steroids have so many side effects. I see you're in Canada. Good luck!

Thank you for replying to my question. I didn’t know it was rare!
A little confusing, sounds like you’re describing Addison’s? My understanding (and please correct me if I am mistaken), your body naturally produces Prednisone but when you are on a dose higher then 7.5mg (per day) your body stops production. The crucial dose is around 7.5mg. Once you go below, your body should start producing again.
I have been in Prednisone for over 30 years and never weaned off and was hoping to naturally reverse the effects of high cortisol caused by the Prednisone.

For us warriors, it's usually Cushing's syndrome caused by steroids, and tapering the steroids really helps. Cushing's disease is rare and caused by a pituitary tumor leading to excess cortisol secretion by the adrenal glands. I hope this helps!