PMR is an autoimmune disorder that causes your immune system to not be able to recognise your body as "self" so it attacks cells in the blood vessels and causes inflammation (probably at least. it is almost the same as GCA but they haven't seen where the damage is in PMR). Pred is used to reduce the inflammation and so relieve the symptoms of pain and stiffness.
Prednisolone is what is called a corticosteroid. The body produces a corticosteroid substance of its own called cortisol. It is essential for the body to work properly but too much isn't good so there is a very complex feedback system in the body which controls how much is made. The body doesn't care whether it is a natural or an artificial corticosteroid it is using so when you are taking enough pred the system signals that the adrenal glands don't need to produce any more. In some ways it is like your heating boiler doesn't produce more heat when the room where the thermostat is warm enough.
If you just take pred for a short time this feedback system just sits there waiting to do its job but when it goes on for months or even years it goes into hibernation. Eventually you reduce the dose of pred below the important level - about 8mg/day. Down to there there is enough steroid around and you function fairly well (not perfectly but well enough). Once you get a bit lower your adrenal glands have to do a bit of topping up - but the system is a bit creaky, it hasn't been in practice and it doesn't work as smoothly. as it should in everybody. If you go slowly enough it usually settles down again and works OK and you manage to reduce to zero if the PMR has gone away and everything is fine although it is a bit wobbly for up to a year after you stop taking pred.
In some people the adrenal glands may not be working as well as they should. Or the feedback system is out of kilter. Then when these people get to the lower doses, typicaly about 5mg, there isn't enough corticosteroid to go round and they start to feel more tired and unwell than at higher doses. For some people going more slowly will work, but for others it doesn't. There is a test to see if your adrenal glands are capable of producing cortisol - but it doesn't tell the doctors if they really are. The symptoms do that. But when you are on pred that is when doctors talk about adrenal insufficiency - the adrenals aren't able to do all they should. In this case it is called secondary adrenal insufficiency.
Addison's disease is a primary insufficiency: it is a long-term endocrine disorder in which the adrenal glands do not produce enough steroid hormones. Symptoms generally come on slowly and may include abdominal pain, weakness, and weight loss. If your adrenal glands don't start working again after reducing your pred then that is the same as Addisons disease although Addisons can be caused by other things too such as another illness.
But PMR itself doesn't turn into or cause the adrenal insufficiency - and although there are a few doctors who think that PMR may possibly be due to adrenal problems there is no evidence one way or the other. They do find that some patients don't have very good adrenal function - but it doesn't apply to everyone.
And yes, pred is the treatment for them all. Pred combats the inflammation in PMR. Pred can be used as the replacement for the cortisol that isn't being produced in sufficient quantities whatever reason it is. Often though another corticosteroid called hydrocortisone (HC) is used. The effect of pred lasts for about 24 hours but that of HC is shorter so you give it 2 or 3 times a day - which is more like the way the adrenal glands would work in nature, several smaller spikes during the day. If you are under a lot of stress - illness, injury, emotional stress, an operation - you may need a bit extra to help cope with it. But in general most people are able to live very well with it.
You will find stuff all over the internet about adrenal insufficiency and ways of making your adrenal glands work properly or blaming adrenal insufficiency for all sorts of things. Most of it is guff - and they are just trying to make money out of you. There aren't any supplements or "natural" treatments that will sort it out.
reposted with permission of, and thanks to....
EileenH
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