Who knows and how can you tell, without goi g to an endocrinologist, if your adrenals are working again..I know it can take up to a year after your at a low enough dose of pred...and sometimes they won’t start up again....found this interesting..
“Adrenal responsiveness.
The longer high dose steroids were given for a disease like asthma, rheumatoid arthritis, polymyalgia rheumatica or inflammatory bowel disease, the more likely that individual will suffer from adrenal insufficiency symptoms on withdrawal of the steroids.
In addition, tapering off the steroids may cause a relapse of the disease that had been treated, causing a combination of disease symptoms overlapping with adrenal insufficiency symptoms. That is why it is very common for steroid tapers to be aborted, with a temporary return to therapeutic doses of glucocorticoids, followed by a slow attempt at tapering if the primary disease is in remission.
One patient mentioned a possible complication in coming off steroids is "Steroid Withdrawal Syndrome" or "rebound effect", which is the body's exaggerated response to removal of the drug. Rebound effect can result in fever, muscle pain and joint pain - making it hard for a patient and his physician to differentiate between withdrawal symptoms and a flare of the disease itself.
The side effects of cortisone, prednisone, and similar drugs are legendary. They include diabetes, osteoporosis, edema of the face, mood swings, stomach ulcers and, very importantly, adrenal suppression. In other words, your own adrenal glands shut off their production of these valuable hormones. Why not, since they essentially have been “told” by the prednisone that the adrenals are no longer needed. This bargain, then, becomes a nightmare as the effectiveness of the drugs wears off, side effects become more serious and the patient is unable to stop taking the medication.
Possibly new on Actemra, what should I know?
PMR misunderstood by the medical community
Taper down to 5mg. Not feeling so good. 
Update on who to believe 
A Rheumatologist who Understands
Have you had the Synacthen Test? This shows if your glands are working at all or in my case sluggishly. I think it’s a case of wait and see, once you know. Mainstream hospitals do the relatively straightforward test. I am seeing my GP next week. I’ll let you know. I don’t want to see an Endo or my stand-in Rheumie, they don’t have anything to pull out of the hat, except messing up my taper, at this stage.
Not IF they are working, whether they are capable of working and producing cortisol when kicked. The entire feedback process is very complex and involves various organis and hormones - and THAT has to settle down as well before cortisol is produced reliably.
My problem now that I’m at 7 1/2....coffee...I love it and when the adrenals are in the state of recovery.....not good...tough to cut back but I gotta for awhile...I’ve read many articles now to learn what’s going on...most say caffeine should be eliminated during an attempt by adrenals to rev up again...how am I gonna rev up? No coffee, Red Bull, nuthin fun...tulsi tea I guess...herbal stuff....ugh