There's probably no answer to this, but why does one person gets an illness and why someone related doesn't fascinates me. By way of examples in 1947 I was 2 and my sisters were 3 and 4. The 3 year old 'caught' poliomyelitis. The other 2 of us were unaffected.
My 2 sisters have lived together all their lives. They both retired, early, in the same year. They eat the same foods, and get the same exercise. 5 years ago the older one ' developed' Type 1 diabetes.
I'm convinced a second reaction to tablets I was taking was a step too far for my immune system. The first reaction was painful rashes on my fore-arms; the second was pains in my leg muscles, both known reactions to the drugs I was taking. I'm not interetsed in litigation. Illnesses happen. The medics say it could be caused by an unknown virus, but that seems to be clutching at straws to me. Does anyone really have a clue as to its cause?
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Thomas45
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It is a mystery what triggers the autoimmune reaction resulting in PMR. There are various theories, such as severe stress/adrenal fatigue, viruses and reactions to drugs.
Prior to onset of my PMR my life was very stressful and then I had a bad reaction to the antibiotic nitrofurantoin, which was severe muscle aches. I then had flu-like symptoms just before acute onset of PMR just after the drug reaction.
If researchers would only question us they might find a cause and this could then help with prevention and treatment
The idea of an unknown virus being the cause has pretty much been ruled out in the case of PMR although it is possible that such a thing might be the trigger. It is an autoimmune disorder - PMR is just a name that describes the symptoms, many painful muscles. Something affects the immune system and causes it not to recognise our body as "self" so some of the cells that normally act as guards and attack invading viruses and bacteria turn on parts of the body and attack them instead. Which disorder you are diagnosed with really depends on the part of the body which is damaged and I think of autoimmune disease as being a shelf with a whole load of symptoms and the shopkeeper hands you a selection - the name given to "your" illness depends on which selection you get and how that compares with illnesses that were described by some doctor many years ago before the associations were understood and they thought they were individual illnesses. They usually gave them their own names (like Crohn's, Wegener's, Sjogren's, Behcet's) - modest or what? Very often people have the symptoms of more than one disease and then are diagnosed as having a "cross-over" autoimmune disorder. Every so often the name is changed (probably to confuse the innocent) as more is found out about the underlying cause.
No one knows what leads to the damage to the immune system. There is no one factor and it is thought it is a range of different factors - genetic, environmental, chemical, infectious - which each nibble away until one happens that breaks the camel's back and the illness manifests. That final one isn't always the same but what is common is that patients have been through a period of high stress shortly beforehand. It isn't just stress but it is a major factor as is evidenced from the frequency with which people find their symptoms get worse in response to stress.
It is predominantly an illness of older people and more common in women - so, since as our bodies age the various hormones change, is there a link there? It certainly isn't a single disorder - as I said PMR is the name for the symptoms not the disease - which is why it is important that the doctor who suspects "PMR" does a range of tests to rule out some more sinister causes. Not all patients with apparently very similar symptoms respond to the 15-20mg daily dose of pred which is sometimes the tie breaker: if the patient responds they have pred-responsive PMR, whatever that is. If they don't then another treatment must be sought (one would hope at least).
Some of the most recent research in GCA has shown that a particular white blood cell, the neutrophil, is present in the affected blood vessels and is the probable cause of the inflammation since it disappears eventually providing a high enough dose of pred is given for long enough. Although it isn't really known how pred achieves its results, it is known that one of the ways pred works in its anti-inflammatory action is on the neutrophils - that's why it works on some forms of inflammation and not others, where neutrophils aren't involved it may not have a point of attack. In GCA though pred works well when used properly and is at present the only proven option in GCA. It will be interesting to find out if neutrophils are also to be found in patients with PMR, just in different blood vessels.
However, that aside, although there is a genetic background and PMR seems to run in families, it isn't a case of there is a gene that means you will get a particular illness, as has been found in some breast cancers for example, just a pattern that makes you more likely to be susceptible. That pattern will be similar but not identical in brothers and sister, except in identical twins who developed as a result of a single egg splitting and developing into two babies. I think, though I'm not 100% sure, that it has been found that there is a higher chance of identical twins who have always lived in the same place developing PMR - if they are split in early childhood and live far apart most of their lives this isn't the case. This does suggest an environmental cause.
Are you sure your sister has Type 1 diabetes? It is very unusual for that to develop that late in life as Type 1 diabetes is also an autoimmune disorder and doesn't often manifest after the late teens/early 20s. It is now being found in middle-aged people though so it is possible. A study in Finland found that if children were given vit D supplements from birth they were less likely to develop Type 1 diabetes (which is very common in Finland) by their teenage years. It is common to find low vit D in many autoimmune disorders and one form of PMR pain can actually be reversed by giving vit D in large doses if the patient is found to have a low blood level - it is one of the tests that should be done in suspected PMR but rarely is. Is it possible that low vit D triggers something that leads to us developing an autoimmune disorder of some sort? The further away from the equator you live the more likely you are to be vit D deficient - and the highest rate of PMR is found amongst people with Scandinavian genes.
You've asked a fascinating question - and as you say, there's probably no answer yet!
Thanks, PMRPro and Badgergirl. I can't remember stress in my case, but on the surface I am a very calm person. It was a blood-pressure reducing tablet that gave me painful rashes on my arms and a Novel Oral Anti-Coagulant (instead of Warfarin) which is known to have one side-effect of leg muscle pains.
My sister definitely has Type 1 Diabetes. About 5 years ago she felt unwell, and after a few days my other sister insisted on ringing what was then NHS Direct one evening. The person she spoke to asked to speak to the ill sister and an ambulance was called. She was in Intensive Care for 5 days during which time she was diagnosed as having Type 1 Diabetes and she is now a dab hand at testing her blood-sugar levels and injecting insulin as necessary..
Yes - I had one BP med a couple of years ago that caused a rash - it started round my neck and then spread outwards and downwards. I was in hospital at the time and by the time they listened to me saying this itch was really unbearable it was down to my waist and most of the way down my arms! It's noted in my notes. They also wanted me to take a statin - I was persuaded to try despite my better judgment. Within a week I could hardly walk - it wasn't just leg muscle pain, I was so weak and felt so ill that 50 yds was almost beyond me and that wasn't even on a full dose! I think it took a year to get over that. This was in the middle of PMR so wasn't the trigger though.
I'm on Sintrom (all for atrial fibrillation, probably caused by the autoimmune part of PMR they think) and a few weeks ago the cardiac consultant offered me the new all-singing/all-dancing new stuff. She hadn't finished the sentence before I declined it! It has just been suggested maybe it DOES need to have blood checks, just like the other anticoagulants, which is really its USP and only benefit. I pointed out that, should I have a bleeding accident it was a lot easier to add in a bit of vit K (or whichever it is) than to pour large volumes of blood into me until the stuff was washed out. She agreed - I know there are other cardiac consultants who feel the same. Having a blood test once a month really isn't a major effort and I really don't fancy the other stuff just to avoid that.
I wonder what causes Type 1 to develop at our age? Must have a read...
Whatever caused your immune system to go into overdrive is probably different from what caused mine to go into overdrive! It could be illness, chronic stress, poor nutrition, trauma, bereavement - any number of things! However, researchers at the Mayo Clinic in the US have now established that there is no shared viral or bacterial component in PMR or GCA, so we will have to knock that hypothesis on the head!
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and how that compares with illnesses that were described by some doctor many years ago before the associations were understood and they thought they were individual illnesses. They usually gave them their own names (like Crohn's, Wegener's, Sjogren's, Behcet's) - modest or what? Very often people have the symptoms of more than one disease and then are diagnosed as having a "cross-over" autoimmune disorder. Every so often the name is changed (probably to confuse the innocent) as more is found out about the underlying cause.
Causes of PMR?
Prednisone causes reduction pain not PMR
Cause of PMR 
Can stress cause a flareup of PMR
Could a fall cause a PMR Flare?
