Little Bluestem,
My GP was not very cooperative or supportive through the whole process, I hope you have better luck. My calcium had been testing high since 1997 (only hit 10.8 once, 10.7 twice - was usually in the 10.3-10.4 range and on rare occasion was actually in the normal range), but for whatever reason GP thought to test 25D and PTH in 2008. That's when I first started getting the message that my "Vit D is low". I'm guessing that since my PTH wasn't high, she didn't pursue it further.
When I requested the three weeks of Ca, 25D, and PTH testing after finding the parathyroid.com website, she initially resisted. Agreed to one test. Of course, my calcium came back in the normal range on that one (fluctuating calcium is one of the "Ten Parathyroid Rules of Norman"). She then agreed to two more weeks of testing, and calcium was high both times. I had calcium, ionized calcium, and PTH run all three weeks. 25D was only run the first week, and it was at 50 ng/mL since I'd been supplementing the prior month. 1,25D wasn't tested until several months later when the endocrinologist got involved.
I was fully prepared to get testing done on my own, there are websites online through which you can do this, not sure how affordable they are or how easy/hard it is to do this since I ended up not needing to. But I think you may be saying you are worried about it becoming "preexisting" - if you test independently I don't think results are reported to any insurance companies (but you'd want to check).
If you have any questions, feel free to PM me, I learned a lot through this process and if I can share any info that makes it easier for others, I am more than happy to.