@charlotte61 , @trina24 , @nancy53

I know having PMR and worrying about GCA is frightening. But in this case, knowledge is power. However, too much knowledge can freak us out and make us think any little thing we experience (headache, for example) means we're getting it. My husband had PMR then developed GCA. The things I would say to watch for is a severe headache that keeps coming back that is then followed by new symptoms, that can come on one at a time. Jaw pain, temple pain, trouble chewing, tender scalp, losing weight, and any change in vision especially blurry vision or feeling like a curtain is coming down over your eye.

I will share our mistake. He had all of these symptoms (except vision issues) that developed over a couple weeks. Our GP said he had TMJ and stress headaches, even knowing he had PMR. Our rheumatologist didn't seem concerned and said to take Tylenol for the headaches. I didn't believe either of them so I put his symptoms and PMR in a Google search and learned all about GCA. Our rheumatologist didn't believe me that he had it. I fought for a biopsy that showed he did. Things got so bad he ended up in the ER with large IV infusions of prednisolone.

I share this to say that if you develop several of these symptoms, or even a recurring bad headache, instead of going to your doctor head to the ER and tell them what you suspect. Insist they run tests and they will. They admitted my husband and he was able to get CT scans and MRIs done on the spot. We would have had to wait weeks if we went through the doctor. Even his doctor recommended going to the ER for that reason. So don't panic. Don't worry about it all the time. Just know what the symptoms are to look for and act on them if they develop. And hopefully they never will. You have an 80% change of NOT getting it.
I've researched this and found that:

About 1 in 5 (20%) of people with PMR will develop GCA
About 50% of people with GCA will have had PMR

This is a good link.
https://www.aafp.org/pubs/afp/issues/2013/1115/p676-s1.pdf
However, they failed to mention anyone on 2.5 mg prednisone or more for over three months should have a DEXA bone scan done and should monitor for osteoporosis.

My husband has PMR and developed GCA. He has been on prednisone for over a year and is still tapering with the help of Actemra injections (for GCA, FDA approved). He's finally down from 80 mg to 17.5.

It's taken a huge toll on his body and he has developed such bad osteoporosis that he's got three compression fractures (one from emptying the dishwasher, the other who knows) and can no longer bend at the waist (at all, no picking things up off the floor and so many other restrictions we don't think about) and can only lift things weighing 5 pounds or less. So it's serious.

I highly recommend anyone on prednisone to have a discussion with their rheumatologist and think about adding an endocrinologist to your list of doctors. We've found ours to be the best for dealing with bone issues. There are things that could have been done early on had we known this information. They could have given him meds to prevent the bone loss. But here we are.